BBQ tick - another attempt to understand

[GT Pony]

20 and 30 weights are fairly close, but the 2018's are the ONLY variant that allows for a change in oil viscosity. 2011-2017's all requires a SINGLE viscosity be run at all times.

Nowhere in the manual does it say 5W-20 is "required" ... it says "recommended".

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[GT Pony]

The standard S197's call for 5W-20 all the time, the Track Pack S197's call for 5W-50 all the time.

And there's no difference in rod and crank bearings, and cam phasors between them. Ford recommended the higher viscosity oil because they know in track use that oil temperatures get much higher (even on the Track Pack with more oil cooling). And for them to say use 5W-50 at all times in the Track Pack pretty much says the "requirement" for thinner oil is all hog wash - it's CAFE driven at the core, not engineering for engine protection driven.

 

[GT Pony]

There are people driving around with spun rod bearings that didn't know it immediately....but hey, do what you want.

Only those that run 5W-20 and beat the hell out of their engine.

Over heated 30 weight provides less protection that properly cooled 20 weight. For real track work, you need proper cooling. Then there's no need to band aid in a higher viscosity to compensate for lack of cooling...

The S197 Track Pack has more water cooling and oil cooling than the non-Track Pack ... yet Ford still said to use 5W-50 because they know higher viscosity oil provides better engine protection. And they expected the Track Pack guys to beat harder on the car. If the oil coolers worked well, then there would have been no reason to use the 5W-50 and just keep the 5W-20, but Ford still recommended 5W-50 because it still gave better protection.

The gain in MOFT from viscosity increase is much more than the small loss of viscosity loss inside the bearing due to increased shearing heat. In other words, even if a higher viscosity oil has more increased temperature in the bearing due to shearing, it still gives more resulting MOFT than a thinner oil with less temperature rise in the bearing.

 

[Condor1970]

If I'm not mistaken, Roush requires the use of 5W-50 when they install a supercharger kit on a Coyote or they will not warranty the installation. There is NO change of the cam phasors, etc ... so how could that all be good if Coyotes were that sensitive to viscosity.

Aha!! That's right. I forgot about that. From what I understand, the 5w50 is needed because of the heat and lubrication requirements of the screw compressor itself, correct?

I'm sure that Roush being directly Ford affiliated had done plenty of testing with 5w50 to ensure proper engine lubrication, including proper phasor operation to ensure no timing issues. So, based on that alone, one could even run 5w50 in a regular NA engine if they really wanted to. I suppose if you live in Dubai during the summer.

 

[TheLion]

If the bearing clearance was at 0.0008 inch (0.8 thousandths), look at how much the localized bearing oil temperature increases from shearing vs a bearing that it at 0.002 inch. From the Coyote service manual, the Gen2 Coyote rod bearing clearance is specified to be 0.0011–0.0027 in and the crankshaft bearing clearance is specified to be 0.0010–0.0018 inch.

Where did that data come from? As posted before, this table shows other numbers. Note that increased RPM actually increases MOFT because the journal bearing is flowing more oil from it's own rotation, which makes the journal ride on a thicker hydrodynamic oil film (the MOFT). I threw in a bonus graph showing that engine RPM has way more effect on oil temperature rise than the engine loads.

0.0008 is a tolerance. Not a clearance. The two are different. Clearance is the specified ideal gap. Tolerance is the variation on that spec. I'm sure you know that. You can state mins and maxes or you can state the nominal with a tolerance. I said before I thought the clearances on the bearings were 0.001 to 0.002ish with a machining tolerance of 0.0008. That's been fairly standard on mod motors for the last 15+ years (it was standard on the 4.6) and what the FP rep told me on the phone. But the clearance is right in the sweet spot for generating the greatest oil film based on linked graphs from KingBearings. BTW that forum link @GT Pony found is all referenced from KingBearings, I found the actual source article here they used: http://kingbearings.com/wp-content/uploads/2014/10/optimization-of-clearance-engine-professional.pdf

But 30 weight isn't going to buy you much over 20 weight, especially when comparing a ACEA A5/B5 spec 20 weight to a SAE 30 weight. Both have a minimum HTHS of 2.9. If one really wants protection for track it sounds like a 40 or 50 weight would be needed for HPDE type use in any of these engines assuming the cam phasors don't get upset. Here's the thing however, if the temps get way up there for the oil, then it will thin out to a viscosity that is well within the range of what a thinner oil would be at cooler temps. So I guess at this point I'm a bit thrown off by FP's statements about the 5.0's sensitivity to oil viscosity. They also claim that the Track Pack S197's had different ECU tuning optimized for 50 weight over the regular 5.0's...not sure at this point if that is true or not and if it's not why in the world they say that? Their ECU tuning is first class and their reliability record exceeds anything after market.

I do know the SS 1LE calls for 5W-30 for street but GM does say to switch to 5W or 0W-40 for track use even on the 1LE with the added cooling after doing a little research. But what still throws me off is statements from Ford Performance and others (engine builder mag had an article on this) on the benefits of thinner oils not related to CAFE such as more uniform distribution of thinner oils within the bearing itself supporting higher loads. Thicker oils with wider clearances typically provide less total distribution of the film but a thicker film, however they are more prone to "squishing out". Thinner oils and tighter clearances provide wider distribution of the film, so there's more film contact area, however the film itself is thinner and less tolerant of distortions and contamination. Thinner oils do transfer heat better and I've seen multiple articles from reputable sources (Driven, Ford Performance, EngineBuilderMag) stating that thinner oil viscosity are better thermal conductors.

These statements seem to contradict KingBearings data...

 

[TheLion]

This is one of my references for using the OE spec oil viscosity:

Some customers are basing their oil usage on the incorrect assumption that Ford and other auto manufacturers only recommend 5W-20 oil in order to increase fuel economy. Using 5W-20 oil can increase fuel economy by about 6/10ths of a percent compared to 5W-30 and more if you are currently using a higher-viscosity oil. This equates to an additional savings of 125 million gallons per year when used in all applicable Ford vehicles. Since its introduction in the 2001 MY, 5W-20 oils have saved up to 640 million gallons of gasoline in the U.S. or an equivalent 5.6 million metric tons of carbon dioxide emissions.

Since any increase in fuel economy may not be noticed by the average motorist, the best reason to use 5W-20 oil is it’s thinner with lighter viscosity and creates less drag on the crankshaft, pistons and valve train. Additionally, the oil pump can move thinner oil more easily, improving oil circulation. The lighter viscosity of 5W-20 oil flows faster at start-up compared to higher viscosity oils, which helps reduce engine wear in critical areas by lubricating parts faster. Valve train components at the top of the engine require immediate lubrication at start-up.

Source: http://performance.ford.com/enthusi...tery-out-of-picking-the-proper-motor-oil.html

Here is another sources that contradicts the notion that the ONLY reason for using lighter viscosity oils is due to CAFE standards:

Reducing the oil clearance between the rod and main bearings and the crankshaft has a number of advantages. A smaller gap spreads the load over a wider area of the bearing surface and distributes pressure more uniformly across the bearing. That’s good, provided the bearing is strong enough to handle it. A smaller gap also decreases the volume of oil that has to flow into the bearing to maintain the oil film between the bearing and shaft.

That’s also good, provided the oil is thin enough (low viscosity) to flow well into the bearing. This also reduces the amount of oil pressure the engine needs, so some extra horsepower is gained by reducing the load on the oil pump.

Source: https://www.enginebuildermag.com/2013/03/bearing-clearances/

I believe at this point most of the negative connotations regarding accelerated wear and thinner oils have far more to do with inadequate boundary layer lubrication due to tightening requirements on limits of ZDDP or MoS2 due to EPA. Heavy viscosity oils have almost no bearing on boundary layer lubrication and that is where 90% of wear occurs. Not in inadequate film thickness. Cams operate in Mixed, so at lower RPMs where most street car engines spend their time, they are in boundary. At higher RPM's they may go hydrodynamic or elastohydrodynamic due to the extreme changes in loading similar to a rod bearing.

The only real issue I see with tighter clearances and thinner oils is the biggest issue I've been suggesting we avoid all along, permanent shear and controlling heat. Both can be accomplished by added cooling and the use of higher quality oil base stocks:

One of the disadvantages of closer bearing clearances is that it can increase both bearing and oil temperatures. That’s no problem as long as the bearings and oil can handle the heat, but if they can’t it increases the risk of lubrication breakdown and bearing failure. That’s why high quality synthetic motor oil is absolutely essential if you are building an engine with tighter than normal clearances....

For high revving performance engines, some bearing manufacturers recommend rod bearing clearances of .002? to .003?, with an absolute minimum clearance of no less than .0015?. The tighter the clearances, the tighter the geometry requirements are for the crank journals (as round, straight and smooth as possible with little or no taper).

Looks like the 5.0's rod bearings are pretty typical in their clearance ranges from the information I have. Your not going to find a 100% unanimous consensus, but they do have a similar theme. The biggest issue with tighter clearances and thinner films is shear and heat. However you can achieve higher volume of flow, use higher quality base stocks and use added cooling to counteract shear and heat while still maintaining the benefits of the thinner viscosity oils. Lower pumping losses, higher power output, better fuel economy.

It's not going to have much effect on rod bearing wear. That's going to occur during cold cranking and the first couple of revs as the engine tries to start before oil pressure is adequate and the oil viscosity is very high. For that you need to rely on EP additives in the oil for protection. It has little to no impact on cam wear or timing chain wear as both spend most of their time in the boundary regime, even at high RPMs, flat tappet engines often stay in boundary hence why they are super sensitive to ZDDP content being high enough.

I still maintain that going to a 30 weight from a 20 weight isn't going to cause issues. They are close enough (and have the same cold temp range) that in a stock or mostly stock 5.0 internally they will have similar performance. In face Euro spec multi-viscosity 20 weights cross into high temp performance range of SAE multi-viscosity 30 weights, having the same HTHS minimum requirements.

2.9 vs. 3.0 HTHS....isn't much and not likely to make a difference as it's only 3.4%. Maybe 2.9 to 3.5, now were talking 17%, much more significant difference. To get a HTHS in the 3.5+ range, you need to go ACEA A1/B1 or SAE 15W-40, 20W-40, 25W-40 & 40+ range.

Nothing below the thicker SAE 40's is going to provide any substantial increase in HTHS performance...a couple of percent. Maybe ACEA A1/B1, which has a HTHS range up to 3.5. But ACEA A5/B5 is 2.9 to 3.2 range which with proper cooling I believe is plenty.

Its like going to a SAE 5W-30 but with requirements for stay in grade that are more stringent than SAE requirements which allow for quite a bit of shear down. I still believe better solution is higher quality base stocks that are more shear resistant (stay in grade) and added cooling to compensate. We are perhaps saying the same thing in the end regarding high temp protection, but taking two paths to get there. Using a thicker oil and just letting it thin out does provide better film strength. But so does using a more temperate stable oil that resists thinning and adding cooling. But one solution is more optimal across the operating temp range than another, making it more street friendly.

 

[TheLion]

Just for reference, since we are on the BBQ Tick thread I still have the following noises:

1. Occasional intermittent light knock when cold at idle, but can't hear it when starting from a stop or driving. Might do it when warm but I don't pay attention as much when warm and tend to focus more on the ticking.
2. A somewhat pronounced ticking (rythmic) when warm at idle.
3. 3000 RPM rattle when cold (I can hold in that RPM and vary throttle and make it louder or quieter), goes away after about the first minute or two of driving.

However TriboTEX did solve the BBQ Tick when starting from a stop. I have not been able to detect that noise since. I've also just recently changed the oil from Mobil 1 5W-20 to Ravenol SFE 5W-20 due to it's PAO baste stocks and extremely good (for a 20 weight) 2.9 HTHS for a little more added protection. So far I have stuck to 5k~6k OCI's but no Blackstone UOA's. I will do a UOA on Ravenol once it comes due probably mid summer 2019. Every single ticker I've seen that's still running has shown good UOA's despite the fact that they sound like something is legitimately wrong just for reference. It's not unique just to the 5.0 either. There are tons of Hemi's and even several LT1's that tick and run fine so it's far from a Ford only problem.

Oil pressure is normal and still in the range it has always been at. About 20 psi to 25 psi at idle fully warmed, varies a bit depending on outside temps and weather or not I just got done with a lot of high RPM WOT. Never goes below 70 psi when WOT during extended high RPM, typically when just normally driving and doing a quick WOT blip it's about 80 PSI, so there's no indication that the 3000 RPM rattle or the occasional intermittent knock at idle has anything to do with rod bearings. You spin a bearing and your oil pressure will go down. Ford performance noted that's how they keep track of rod bearing health in some of their track cars. They log oil pressure readings and establish a base line new. Once it starts to change significantly thats an indicator they are up for new bearings.

Fuel economy is stellar for this type of car with this gearing, I can still get up to 29~30 mpg on a known stretch of highway only previously was able to get 25~26 on before TriboTEX. Occasionally still get a burning oil smell after some hard driving, I do see some oil / grime accumulation around the dip stick tube, so maybe one of the bolts is a bit loose or a bad valve cover gasket. Had this issue since I first bought the car and it's dealership noted along with the 3000 rpm rattle.

Had a catalytic converter replaced around 23k miles under warranty. Bank 1. Threw a P0420 code and CEL illuminated like it should. No noticeable drive ability symptoms except some hickups in RPM dropping at idle more than normal prior to the dealer replacing it.

I also still get the "fairy dust" in my oil catch can every time I empty it after about 1,000 mile intervals just like on the Corvett forum I posted a link to a while back. I asked Ford Performance if they saw this and they said yes it's normal. Car is under a 100k/7yr ESP for power train, so if the engine eats itself, I got 4 years and 75,000 miles for that to occur before I'd be footing the bill thanks to Ford Performance warranty preserving power pack, which I've already had to use the warranty for to get the cat replaced (no issues, dealer treated it like a stock car since they did the install).

I'm running the following regarding engine related modifications:

1. Ford Performance Power Pack 2 installed at 17k. Car has NEVER had any other ECU calibration other than stock and Ford Performance, at least not since I've owned it.
2. Corsa Sport cat back exhaust that was on the car when I purchased it last December with 5,600 miles on the clock.
3. JLT 3.0 oil catch can.
4. TriboTEX Diesel concentration added at 21k.

Other than that the engine hasn't been touched. With my modifications I'd estimate I'm making around 465 to 475 hp at the crank. I only have run 93 pump gas since I've gotten it. BTW the rattle / knocking at 3000 RPM could be piston slap or it could be actual light pinging when the engine is open loop (mild pinging isn't harmful). I've never once heard detonation or "marbles" once warm under any condition, weather high RPM WOT or cruising at 75 on the highway, even going 35 down town in 5th gear a little under 1500 rpm.

Yup my engine is clanky, it literally sounds like a sowing machine. TriboTEX initially quieted it down, but after about 500 miles it actually made the noises more pronounced. Not louder but more distinct. I believe this is likely that once the ultra lubricious tribo film forms, parts are going to slide more easily and hence come to rest at a slightly higher velocity as there is less resistance to their motion. So valves are going to experience more of the springs energy (like using a slightly stronger spring), piston rings are going to slide more easily possibly allowing them to flop around a bit more etc.

That's where Archoil and CeraTec differ, they have additives that slightly alter the oils properties where TriboTEX does NOT interact with your oil at all. It has no chemical friction modifiers. It is only a DLC film and uses the oil as a carrier fluid like Archoil and CeraTec. Honestly, a car guy whose sensitive to noises and not familiar with the 5.0 and it's quirks would think something is seriously wrong with my engine. Oh and I burn only about 1/4 to 1/3 a quart of oil in the last 4,500 mile oil change when I initially added TriboTEX. Prior to that it was about 1/2 quart. So oil consumption did go down even further. And that's with lots of WOT high RPM driving on back roads. In both very cold and very hot conditions.

There's no reason for this engine to throw a rod bearing or have any major failures at this point given there's no CEL, no abnormal oil consumption, excellent fuel economy, awesome power / throttle response, perfectly smooth and consistent idle. But it sounds like it's dying sometimes...at least to me. My wife doesn't notice most of these nosies at all. So I'll continue this experiment in testing the reliability of Ford's 2nd generation 5.0L V8 when properly maintained. I'm also running the OE GT350 style paper conical air filter and will continue to use paper due to much better filtration than oiled or dry re-usable. I will also continue to use the OE FL-500S filter that meets USCAR36 requirements. Wear is directly related to particular size and concentration as well as the EP additive packages and bearing clearances. All play a role. Throw any one out of whack and you will have accelerated wear. TriboTEX should compensate should one get out of whack, but I'd rather not find out what the compensating limits are, so keep it clean and run it hard!

 

[TheLion]

Just some food for thought also as to how so many of these noises could actually be benign despite our perception that many of them indicate a serious problem:

1. Oil pressure is 3.5x higher in the upper RPM ranges (70 to 80 psi) than in the lower RPM ranges (20 to 25 psi) where 99% of the "death ticks / rattles / knocks" occur, so films are far weaker and flow volume is quite a bit lower permitting less "hydraulic cushioning". This is likely why the BBQ tick doesn't occur at higher RPMs as the hydraulic cushioning of the big ends of the rods side to side prevents contact where it may not at lower RPM / lower pressure. Some have also eliminated that noise by running 40 or 50 weight oils, but 30 weight doesn't seem to be enough of an increase to affect the noise much.

2. Clearances are set up to deal with the added heat of a high RPM 32 valve DOHC V8 running low viscosity oil and tight clearances (the hottest running engine configuration you can get unless you add more cylinders!), so that means there's likely some extra slop on rod end side to side clearances, piston to cylinder wall clearances etc. where there's a lot of expansion due to heat which makes it more clanky at idle

3. Skeletal cast aluminum blocks and stainless headers are GREAT conductors of every sort of noise the engine can make

4. There are cars out there with a very pronounced ticking that are now super charged and still running strong with nearly 25k+ miles on them like mine.

5. In several cases where a new short block was warranted by the dealer, the tech's couldn't actually find anything wrong with the "ticking short block"....maybe they missed something, but everything they did check was in spec and there was no visual signs of issues on the rod bearings from the one with photos.

6. Very similar ticks / rattles / knocks occur in engines from other manufactures as well such as the Dodge Hemi 5.7 and 6.4 (tick and rattle) or the Chevy LS / LT (ticking) engines.

7. There are track cars that are noisy and clanky as can be that run just fine beating the living crap out of it since it was new.

And this is why it's nice to have a warranty and why I advocate only going with Ford Performance or Roush. If you do end up with an actual major failure, by staying with Ford Performance / Roush, you have a warranty that is still in tact that will cover a Ford mfg or design defect.

BTW, some one mentioned Roush requiring 5W-50 for any super charged applications...their web site says 5W-20 for all three of their Coyote crate offerings. The only 5.0's stating to use 5W-50 are the following:

1. S197 Track Pack GT's
2. Boss 302's with the Road Runner 5.0 (special limited production variant)
3. Ford Performance Aluminator 9.5:1 compression 2nd Gen 5.0's for super charging applications with main bearing clearances of 0.027 - 0.069 mm: https://performanceparts.ford.com/download/instructionsheets/FordInstShtM-6007-A50NA.pdf

Seems kind of strange to run 5W-50 in an engine with main bearing clearances of 0.0011 to 0.0027 but also run that same oil viscosity in an FI engine with much larger clearances in the 0.027 - 0.069 mm range. I'm just trying to make sense of these recommendations that are seemingly incoherent.

I wonder if there is more than one reason for these variations:

1. Some applications requiring higher viscosity oils like the S197 Track Packs may be solely to compensate for expected high heat loads. Running a lower viscosity would not result in engine failure except in cases of excessive thermal loading as the clearances are actually optamized for 5W-20 / 5W-30 low viscosity oils.

2. Other applications like the Ford Performance Aluminator Crate engines are due to actual differences in bearing clearances. Running a lower viscosity would result in engine failure.

https://www.roushperformance.com/engines (at the bottom for the Ford Coyote V8 engines).

Why in the heck would Roush suggest 5W-20 for a non-street legal crate engine....maybe as I've said all along there are reasons beyond just CAFE. But of course because some unknown person on the internet said so, it must be true!

 

[TheLion]

I just want to play devils advocate a little longer here regarding using signficiantly higher viscosity oil (I have no issue with running 5W-30 for track, but I am sticking to it that any higher barring some extreme shear conditions, you could actually be inducing oil starvation). It's common practice to run one viscosity grade higher for very hot climates or heavy towing etc.)

And here is the installation of the Roush Super Charger kit (670 hp version): https://www.roushperformance.com/media/parts/manuals/421823-5L-Phase1-ROUSHCHARGER-kit.pdf

No mention to drain the oil and use 5W-50...no requirement to change oil viscosity...and the warranty statement: https://www.roushperformance.com/me...ited-Powertrain-Warranty-Upgrade-12-17-15.pdf

...no mention of 5W-50 there either. Hummmmm...people posting misinformation about this manufacturer requiring this oil or that oil to support their claims and it we just can't seem to find it when we actually search.

And also the Phase 2 727 HP super charger kit...on the stock bottom end. No mention of 5W-50 there either on their website nor in the installation instructions. One would think if it was required it would be IN the INSTLLATION instructions or IN warranty statement or LISTED on their web site. So if it required but they don't tell you...how are you supposed to know?

How about the Ford Performance Super Charger Kit: https://performanceparts.ford.com/part/M-6066-M8627

2015-2017 Ford Mustang GT with 5.0L 4-Valve Engine w/ Manual Transmission Important Notes: • Before installing your Mustang Supercharger Kit, please read the installation manual and verify that all items are present. If you are missing hardware or have any questions, please contact Ford Performance at 1-(800) FORD788. • Premium fuel (91 octane or higher) is required to prevent “spark-knock” or detonation under certain operating conditions. • The use of fuel additives (i.e. octane boosters) is not recommended. There is a possibility that these chemicals can damage your engine and cause drive ability issues with your vehicle. • Operating your engine without the Ford PCM re-calibration will result in engine damage or failure and will void your warranty. • Manual transmission only available at this time.

No mention of changing oil viscosity in there either (I did a search through the installation instructions as I did for the Roush instructions). No mention of 5W-50 or even 5W-30 on their site either. Looks like the only engines they are suggesting 5W-50 for is their Aluminator crate engines that use larger bearing clearances....

I wonder if the S197 Track Packs did actually use different clearances in the bearings for track work. The Boss 302's Road Runner 5.0 certainly did NOT use the same bearing clearances. It required 5W-50, there is no Boss 302 variant I am aware of that mentioned anything but 5W-50. The Voodoo 5.2 also is a track engine and requires 5W-50, bearing clearances are NOT the same as the regular 5.0.

Larger clearances and higher viscosity oil facilitate cooler running bearings even if the thermal transfer is not as good with higher viscosity oil. Larger clearances are also more tolerant of distortion. Ford may have been playing it safe in the first gen S197 Track Packs. It would not be hard to use a bearing with slightly larger clearances and a different PCM calibration. Ford Performance claims the PCM calibration for Track Pack S197's was indeed different than regular GT's due to different oiling requirements. Not one person has offered proof that they are the same engine.

Why would we run 5W-50 in a 0.0011-0.0027 bearing clearance but then use 0.0027 to 0.0069 clearance for the same oil? There's no way both clearances are optimal for 5W-50. The user manual seems to support the idea that the Track Pack S197's may be slightly different internally, even if it were only a PCM calibration. They call for 5W-50 all the time. I can see changing one viscosity grade to compensate for heat under abnormal use conditions. The 2018's call for going to a 30 weight for track. So does the Camaro SS, it calls for going from 5W-30 to 5W-40 for track. But 20 to 50 is a huge jump without any adjustment to clearances unless the first gen 5.0's run super hot....

I suspect the clearances are tailored for the application. Either that or Ford knows their 5W-50 shears down to a 5W-30 rapidly and it was a compromise for their limited ability to produce a shear resistant 50 weight. The 2nd gen's run 5W-20 for both street and track use including with a SC while the 1st gen's may have required different clearances for the two applications due to design limits. They simply aren't the same engines. Same thing with 3rd gen's. But they generate more heat than the 2nd gens due to higher operating RPM, higher average power and additional heat generating components like the HPFP. It all adds up and I can see why requirements would change. The Aussie 5.0's provide some compelling evidence however that 5W-30 should be ok, they literally changed the viscosity grade requirements with a user manual revision. But there is still no call for anything as heavy as 40 or 50 weight even in the Aussie 5.0 manuals even for track (2015-2017's).

Subtle differences you or I may not be privey to can have a substantial impact on function. The only concession I might make willingly is running 5W-30 for track days in a 2nd gen 5.0 to compensate for heat to get a higher HTHS. Either that or use RedLine's 5W-20 which has a HTHS of 3.0, which is about what most off the shelf 5W-30's are anyway, but without going out of spec for 5W-20 and meeting ACEA A5/B6 requirements. I find it very interesting that none of the SC applications make any mention of moving up a grade in oil weight...very odd.

 

[GT Pony]

0.0008 is a tolerance. Not a clearance. The two are different. Clearance is the specified ideal gap. Tolerance is the variation on that spec. I'm sure you know that. You can state mins and maxes or you can state the nominal with a tolerance. I said before I thought the clearances on the bearings were 0.001 to 0.002ish with a machining tolerance of 0.0008. That's been fairly standard on mod motors for the last 15+ years (it was standard on the 4.6) and what the FP rep told me on the phone. But the clearance is right in the sweet spot for generating the greatest oil film based on linked graphs from KingBearings. BTW that forum link @GT Pony found is all referenced from KingBearings, I found the actual source article here they used: http://kingbearings.com/wp-content/uploads/2014/10/optimization-of-clearance-engine-professional.pdf

I quoted the Coyote Gen2 bearing clearance specs from the service manual. This is no +/- given by Ford, but rather the min to max range. Of course that could be transferred into a nominal with a +/- tolerance. Regardless, the graph I posted clearly shows that tighter bearing clearances (especially as they start getting below 0.002") start causing the localized oil temperature inside the bearing to increase significantly.

Noted chart 7 and the corresponding text in that PDF link you gave above. They say:
"The third disadvantage of tight clearance is
excessive heating of the oil. The friction energy
generated by the bearing at high rotation speeds
may heat the oil to a temperature above its
maximum limit (e.g. 500 °F for synthetic oil). The
graph in Figure 7 illustrates the effect of clearance
on oil temperature rise (delta T)."

They list some other disadvantages of tight bearing clearances too. So some sources say there are advantages to tight bearing clearances, and others say there are disadvantages.

I wonder if some of these Coyote engines with problems have too tight of rod and/or crank bearing clearances? And that could be a reason why some guys report that their bearings go bad (and the clearance then gets way large from damage) at pretty low mileage.

IMO, bearing starting out too tight are going to get damaged because the MOFT will be very small which will probably cause metal-to-metal contact and then damage the bearing. It's pretty hard to damage bearings with a little too much clearance because the MOFT will always be larger in bearings with more clearance (look at the graphs showing MOFT as a function of bearing clearance). More MOFT always give more protection between metal parts.

But 30 weight isn't going to buy you much over 20 weight, especially when comparing a ACEA A5/B5 spec 20 weight to a SAE 30 weight. Both have a minimum HTHS of 2.9. If one really wants protection for track it sounds like a 40 or 50 weight would be needed for HPDE type use in any of these engines assuming the cam phasors don't get upset. Here's the thing however, if the temps get way up there for the oil, then it will thin out to a viscosity that is well within the range of what a thinner oil would be at cooler temps. So I guess at this point I'm a bit thrown off by FP's statements about the 5.0's sensitivity to oil viscosity. They also claim that the Track Pack S197's had different ECU tuning optimized for 50 weight over the regular 5.0's...not sure at this point if that is true or not and if it's not why in the world they say that? Their ECU tuning is first class and their reliability record exceeds anything after market

In almost every case, xW-30 will have a higher HTHS than a xW-20. Therefore, 30 will indeed protect better. And I do agree that if anyone is concerned about engine protection when pushing the engine hard, and they still want to run a 5W-20, then look for a boutique oil in 5W-20 that has a HTHS up where most 30 weights are. Engine protection stems for the most part from the HTHS quality of the oil - and of course any "anti-wear" additives.

Again, I really don't think the "sensitivity" of the cam phasors are of any concern. Would Roush say use 5W-50 on their blown cars for warranty purposes and Ford Performance recommend 5W-50 in certain applications if it was a big phasor deal? And like said before, running thicker oil may increase oil temps somewhat higher under the same high RPM conditions, but you are still coming out ahead on the protection factor because the MOFT is still greater inside the bearings with the hotter but still thicker oil. Many car manufacturers recommend a thicker oil for track use. If the thicker oil heated up to the point that resulted in less MOFT than running the thinner oil on the track, then they would never recommend using thicker oil for track use.

I do know the SS 1LE calls for 5W-30 for street but GM does say to switch to 5W or 0W-40 for track use even on the 1LE with the added cooling after doing a little research. But what still throws me off is statements from Ford Performance and others (engine builder mag had an article on this) on the benefits of thinner oils not related to CAFE such as more uniform distribution of thinner oils within the bearing itself supporting higher loads. Thicker oils with wider clearances typically provide less total distribution of the film but a thicker film, however they are more prone to "squishing out". Thinner oils and tighter clearances provide wider distribution of the film, so there's more film contact area, however the film itself is thinner and less tolerant of distortions and contamination. Thinner oils do transfer heat better and I've seen multiple articles from reputable sources (Driven, Ford Performance, EngineBuilderMag) stating that thinner oil viscosity are better thermal conductors.

These statements seem to contradict KingBearings data...

Bottom line, is you simply have less MOFT to play with when using a thinner oil. Every technical write-up and SAE paper I've seen shows that thicker oil always gives more MOFT inside a journal bearing. It's just how journal bearings operate.

I don't know if I buy that "thinner oils transfer heat better". Heat transfer through conduction can also be dependent on the MOFT layer thickness, so they may mean that a thinner oil film will transfer heat better to the bearings themselves, but not be so dependent on the actual oil viscosity. If you could link up some of those articles you mention, that would be great because I'd be interested in seeing what they say about heat transfer as a function of viscosity.

 

[GregO]

0W-20 Castrol Professional E or SAE Extended Performance.
Honestly, this stuff is as good as it gets. It’s close to a 30wt out of the bottle.
-47 F pour point.....
I can’t be the only one running a 0W.

 

[GT Pony]

I just want to play devils advocate a little longer here regarding using signficiantly higher viscosity oil (I have no issue with running 5W-30 for track, but I am sticking to it that any higher barring some extreme shear conditions, you could actually be inducing oil starvation). It's common practice to run one viscosity grade higher for very hot climates or heavy towing etc.)

And here is the installation of the Roush Super Charger kit (670 hp version): https://www.roushperformance.com/media/parts/manuals/421823-5L-Phase1-ROUSHCHARGER-kit.pdf

No mention to drain the oil and use 5W-50...no requirement to change oil viscosity...and the warranty statement: https://www.roushperformance.com/me...ited-Powertrain-Warranty-Upgrade-12-17-15.pdf

...no mention of 5W-50 there either. Hummmmm...people posting misinformation about this manufacturer requiring this oil or that oil to support their claims and it we just can't seem to find it when we actually search.

Bottom of page 2: 5W50 oil is required.
https://www.roushperformance.com/media/parts/manuals/422090-instructions.pdf

Also, look at page 73. 5W50 required for warranty. A "5W-50" sticker is put on the oil fill cap to warn someone not to put thinner oil in the engine.

 

[GT Pony]

Looks like the 5.0's rod bearings are pretty typical in their clearance ranges from the information I have. Your not going to find a 100% unanimous consensus, but they do have a similar theme. The biggest issue with tighter clearances and thinner films is shear and heat. However you can achieve higher volume of flow, use higher quality base stocks and use added cooling to counteract shear and heat while still maintaining the benefits of the thinner viscosity oils. Lower pumping losses, higher power output, better fuel economy.

Tighter bearings flow LESS oil naturally due to their own rotation (ie, take away any pressurized oiling source). There are two factors in the total oil flow going through a journal bearing. 1) the "hydrodynaic flow", which is what the bearing naturally flows (ie, it's natural side leakage) simply due to it's rotation, and 2) the added flow produced by the pressured oiling system. So Total bearing flow (side leakage) = hydrodynamic flow + pressurized oil flow.

But since the bearings are feed by a pressurized oiling system from the positive displacement oil pump, that does help them flow more oil, and a larger clearance will also flow more oil from the pressure source factor than a tight clearance. Keep in mind that if the oil pump's max pressure output is say 100 PSI (as controlled by the pressure relief valve - No ECU oil pump control on the Coyote), then a larger clearanced bearing is going to flow more oil both from it's natural rotational flow (ie, flow without a pressure source), AND it's also going to flow more oil from the pressurized factor.

So larger clearance bearings will always flow more oil in a given oiling system. Of course the indicated oil pressure with larger bearing clearances will be lower however (if using the same oil viscosity), but the oil pump is still putting out the same oil volume per engine RPM curve (basic characteristic of a positive displacement oil pump). If the bearing clearance really gets large, that's where you have to ensure that the oil pump can put out enough volume to adequately feed and cool all the bearings at max flow conditions - ie, that's why they invented "high volume" oil pumps.

As far as all these variable volume ECU controlled oil pumps (which the Coyote doesn't have) ... it's all a bunch of complicated BS to saves 0.001 MPG (again car makers striving to meet CAFE), and I'd rather not have one on any vehicle I own.

 

[GT Pony]

I also still get the "fairy dust" in my oil catch can every time I empty it after about 1,000 mile intervals just like on the Corvett forum I posted a link to a while back. I asked Ford Performance if they saw this and they said yes it's normal.

Did they say what it's from? I've never seen fairy dust in my catch can - and others here on the forum report never seeing it. I'm really wondering if these guys you're talking to at Ford Performance always know what they are talking about - or are they just deflecting with canned answers to questions..

 

[GT Pony]

BTW, some one mentioned Roush requiring 5W-50 for any super charged applications...their web site says 5W-20 for all three of their Coyote crate offerings. The only 5.0's stating to use 5W-50 are the following:

1. S197 Track Pack GT's
2. Boss 302's with the Road Runner 5.0 (special limited production variant)
3. Ford Performance Aluminator 9.5:1 compression 2nd Gen 5.0's for super charging applications with main bearing clearances of 0.027 - 0.069 mm: https://performanceparts.ford.com/download/instructionsheets/FordInstShtM-6007-A50NA.pdf

Seems kind of strange to run 5W-50 in an engine with main bearing clearances of 0.0011 to 0.0027 but also run that same oil viscosity in an FI engine with much larger clearances in the 0.027 - 0.069 mm range. I'm just trying to make sense of these recommendations that are seemingly incoherent.

Just goes to show that running a thicker oil in tighter bearings is possible and even sometimes recommended ... because again, regardless of the bearing clearance, a thicker oil will always give a greater MOFT.

Only thing you have to worry about with thicker oil is the cold end of the spectrum and ensure they are not too thick for cold starts.

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