0w40?

[Chameleon]

If Ford torture tested the Fiesta, you can bet your ass the 'durability" was take into account on the Mustang. :doh:


"The tests extended over more than a half million miles on test tracks and in laboratory conditions ranging from -40 to 180 degrees and engineers evaluated the Fiesta’s performance over 745,000 miles on public roads. A global car needs to be prepared for the most extreme use and global conditions to ensure it excels in day-to-day performance over the life of the vehicle.

“A combination of high-tech laboratory simulations, demanding test-track trials and real-world evaluations helps us deliver a durable Ford Fiesta that owners can be confident will survive the worst they can throw at it throughout its lifetime,” said Glen Goold, new Fiesta global chief program engineer, Ford of Europe."

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[Ctease]

I would argue the best operating viscosity is known by engineers. But viscosity of oil changes due to many factors. So the known best viscosity becomes a moving target.

The factory might be aiming for 300yrds, cold weather guy 250 and performance driver aiming for 350. Nobody is getting more or less protection their target is just in a different location.

Advanced oils, higher mechanical tolerances and oil cooler allow manufacture to say 5w-20 will shoot most targets. Diverting from recommended grade could put yourself in a situation to miss the target and lose performance. And I think thats why people are saying follow the direction provided by Ford. If you don't care rules and use some common sense you can improve the selection. But I have a feeling common sense is less common these days.

 

[spiller]

Interesting topic. I have always used 5w40 in my track cars but have never tracked a new/modern car regularly enough to consider that a lower weight oil might be called for. I'm here for the popcorn.

 

[TomcatDriver]

Dedicated track use...that is a lot more than what is factored into the durability cycles on the dyno and in vehicle. The engine isn't going to disintegrate or suffer major issues doing a track day on 5W20. Should you go to it on fresh oil? Absolutely. The additives that allow the oil to continue to lubricate effectively at high temperatures are at their best. If it's a track day car and you're doing a bunch per year and very little street driving, it makes sense to go to a heavier oil like 5W50. It's also generally a good assumption that anyone tracking the car that frequently is probably pretty skilled and will put more heat into the oil than the guy who does it very occasionally, thus requiring a oil that maintains higher viscosity better.

Used to work in that department. Still in the industry but doing other things now.

And since the OP said he tracks his car...that would seem to support the heavier oil choice.

 

[ForTheHordeKT]

I don't know, I'll stick to the oil they recommend myself. I was bothered by seeing a high oil pressure this winter though on starts, didn't see it get up there that high when I bought the car over last summer. But a quick little "Is it just me or is anyone else getting this in cold weather?" kind of question calmed my concerns down about it. I just don't get on it too hard until I see the oil pressure drop as it warms up more. Now that our weather is warming up again, I'm not seeing it jump all the way to 85 or 90psi when I first start her up.

 

[GT Pony]

I don't know, I'll stick to the oil they recommend myself. I was bothered by seeing a high oil pressure this winter though on starts, didn't see it get up there that high when I bought the car over last summer. But a quick little "Is it just me or is anyone else getting this in cold weather?" kind of question calmed my concerns down about it. I just don't get on it too hard until I see the oil pressure drop as it warms up more. Now that our weather is warming up again, I'm not seeing it jump all the way to 85 or 90psi when I first start her up.

That's just normal oil pressure behavior when the oil is cold and thick. These cars use a positive displacement oil pump, so it takes more pressure to push the same volume of oil (per engine RPM) through the engine when the oil is cold and thick.

 

[Commbubba19]

0w oil will flow much better and maintain proper viscosity at 0* Celcius vs 5w.

[ame]

This is at -30 as an example. The pour points of 0w is around -50 while 5w is around -42ish. Depends on brand.

If you are in an area of the country that does not see temps that low, there is no need for a 0w oil. 5w is perfectly fine.

Now, regarding the 20 vs 30 vs 40 at 100*c or 212F, that is important. But something you guys haven't mention is oil pressure in relation to the temp and viscosity.

a 20w at 212 is 20w, but at 260, it's like a 5-10w. You can see this in various charts for oil information. 150*C or around 300F (yes that's beyond what most engines will see but not by much on certain track environments) you can get as low as 2-3 viscosity.

So yes, if you're running on a track for 20 minutes+ and using a 20w, yes your lubrication might very well be fine, but i guarantee your oil pressure is likely low. That is when you should move to a 30 or 40w.

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