Oil consumption got worse. Not sure what to do. Should I sell the car?

mustang1 · Oct 19, 2017

UnhandledException said:
How bad is it to do frequent engine braking as far as oil consumption goes? Since changing the oil, I am driving more normal and after 100 miles, the oil color is still clean and did not move down even a mm. I m not doing engine braking at high rpms, after running up gears at high rpm, I used to hold the gear now I am just upshifting instead.

looking at the image for PCV Valve Operation

it would appear to me that you could get some degree of oil consumption both at engine braking and WOT. engine braking is high vacuum, low flow. Not zero flow. And WOT is pressuring the crankcase, pushing air and vapor into intake manifold.

And that's aside from the piston rings, oil control rings, and valves.

MrCincinnati · Oct 19, 2017

UnhandledException said:
How bad is it to do frequent engine braking as far as oil consumption goes? Since changing the oil, I am driving more normal and after 100 miles, the oil color is still clean and did not move down even a mm. I m not doing engine braking at high rpms, after running up gears at high rpm, I used to hold the gear now I am just upshifting instead.

I ran a largely non scientific experiment where I stopped engine braking and/or spending extended periods at high rpm low load (i.e. 5k rpm lightly on and off throttle). My oil consumption lessened, but still continued... probably due to the occasional WOT and habitual/necessary rev matching on downshifts etc.

Next I removed my FP passenger side catch can and continued the above driving habits - oil consumption halted completely.

Then I started driving a bit more aggressively, but still not lingering above 5k for extended periods or heavy engine braking... oil consumption resumed but much lighter than in any of the above scenarios where it was occurring.

GBGT350 · Oct 19, 2017

My car uses about 1/2 quart every 1,000 miles. I have almost 8,000 on it now. The odd thing is my engine uses no oil at all on track days. Mine uses oil while taking it easy driving around town.

[ame]

[ame]

[ame]

[ame]

GT Pony · Oct 19, 2017

MrCincinnati said:
Next I removed my FP passenger side catch can and continued the above driving habits - oil consumption halted completely.

Hard to imagine because the catch-can itself shouldn't cause any flow control changes, especially the FP catch-can which is just a big open cavity with a screen inside it, and it has very short hoses between the PCV valve and intake manifold. The OEM PCV valve in the passenger side valve cover does the flow control.

When doing experiments like this, people need to do it for many thousands of miles with a constant configuration to get a true indication of the effects.

GT Pony · Oct 19, 2017

GBGT350 said:
My car uses about 1/2 quart every 1,000 miles. I have almost 8,000 on it now. The odd thing is my engine uses no oil at all on track days. Mine uses oil while taking it easy driving around town.

Oil level stays constant due to possible fuel dilution? Give your dipstick a smell for gasoline next time to see.

GBGT350 · Oct 19, 2017

GT Pony said:
Oil level stays constant due to possible fuel dilution? Give your dipstick a smell for gasoline next time to see.

There's no evidence of fuel in my oil.

MrCincinnati · Oct 19, 2017

GT Pony said:
Hard to imagine because the catch-can itself shouldn't cause any flow control changes, especially the FP catch-can which is just a big open cavity with a screen inside it, and it has very short hoses between the PCV valve and intake manifold. The OEM PCV valve in the passenger side valve cover does the flow control.

When doing experiments like this, people need to do it for many thousands of miles with a constant configuration to get a true indication of the effects.

I agree the experiment was non scientific - however it is financially significant given I don't have to buy a quart of oil this week ;)

mustang1 · Oct 19, 2017

GBGT350 said:
My car uses about 1/2 quart every 1,000 miles. I have almost 8,000 on it now. The odd thing is my engine uses no oil at all on track days. Mine uses oil while taking it easy driving around town.

what is a typical Avg MPG and total miles for track days ?

UnhandledException · Oct 19, 2017

I think the problem is pistons are designed with an optimum CHT in mind that is for track use. Things expand as they heat up and if you are redlining while CHT is 200F, this oil leakage is bound to happen. If it sealed so well for that temperature the engine wouldnt last in track where CHT probably exceeds 230-240F.

That being said this is probably why there is cars like GT3 or 458 with a titanium piston and rod and extremely stiff crankshaft made of steel alloy. GT3 revs to 9000 rpm and has substantially more compression ratio yet it doesnt consume any oil in city and about half a quart in a track day.

Offboost · Oct 19, 2017

UnhandledException said:
I think the problem is pistons are designed with an optimum CHT in mind that is for track use. Things expand as they heat up and if you are redlining while CHT is 200F, this oil leakage is bound to happen. If it sealed so well for that temperature the engine wouldnt last in track where CHT probably exceeds 230-240F.

That being said this is probably why there is cars like GT3 or 458 with a titanium piston and rod and extremely stiff crankshaft made of steel alloy. GT3 revs to 9000 rpm and has substantially more compression ratio yet it doesnt consume any oil in city and about half a quart in a track day.

FYI there are no titanium pistons, there are titanium connecting rods and forged steel crankshafts though. Neither of these will change enough from cold to hot to consume oil. The ring gaps though will change when heated and the piston to cylinder wall decrease with more temp as well. Along with a tighter ring seal against the cylinder wall under load etc.

mustang1 · Oct 19, 2017

Offboost said:
... The ring gaps though will change when heated and the piston to cylinder wall decrease with more temp as well. Along with a tighter ring seal against the cylinder wall under load etc.

how long does it take the gt350 engine to reach full operating temperature? Similar numbers on the gauges compared to say cruising the highway for half an hour ?

TDC · Oct 19, 2017

UnhandledException said:
So you dont have the PCV fitting they sent me.... with the fitting I have there is no way for car not to consume too much oil. I spoke to 2 independent mechanics and as soon as they saw the setup they said that will create excess vacuum and cause excess oil consumption in a high compression engine.

No fitting like u received; only the factory fitting was ever used.

SVTinAR · Oct 19, 2017

GT Pony said:
Hard to imagine because the catch-can itself shouldn't cause any flow control changes, especially the FP catch-can which is just a big open cavity with a screen inside it, and it has very short hoses between the PCV valve and intake manifold. The OEM PCV valve in the passenger side valve cover does the flow control.

QUOTE]

My thoughts on the subject too. Although I've only had my GT350 for about 400 miles it has collected quite a bit of oil in the JLT pass side strainer already, which I immediately mounted on it. I drive conservatively - probably haven't been above 5,000 rpm yet. However, my 12 GT did about the same and it only ran down about 1/2 quart in 4,000 miles between changes. Leaving the stock Ford PVC valve in place and just replacing the pipe with a unit with a strainer shouldn't affect engine performance in any way I can imagine. If anyone knows how it does so, I would be interested in hearing about it.

Offboost · Oct 19, 2017

mustang1 said:
how long does it take the gt350 engine to reach full operating temperature? Similar numbers on the gauges compared to say cruising the highway for half an hour ?

That question has way to many variables to give any kind of accurate answer.

Depends on ambient temp, wind speed, wind direction, road speed, raining, not raining, load, current rpm, what gear the car is in etc etc.

That being said on a what we hopefully can all agree on is on a average 70 degree day from a cold engine under normal cruising it usually takes about 15 or so minutes under normal driving for the oil temp to reach 180 after that the engine is fully warm. I do not go off of cylinder head temp because the engine oil takes a lot longer to heat up than coolant temps.

mustang1 · Oct 19, 2017

Offboost said:
That question has way to many variables to give any kind of accurate answer.

Depends on ambient temp, wind speed, wind direction, road speed, raining, not raining, load, current rpm, what gear the car is in etc etc.

That being said on a what we hopefully can all agree on is on a average 70 degree day from a cold engine under normal cruising it usually takes about 15 or so minutes under normal driving for the oil temp to reach 180 after that the engine is fully warm. I do not go off of cylinder head temp because the engine oil takes a lot longer to heat up than coolant temps.

15 minutes is a lot of time. That's nearly 15 miles on the highway. In the city, that's a lot of stop & go on an engine that isn't fully hot.

Oil consumption got worse. Not sure what to do. Should I sell the car?

mustang1

Well-Known Member

MrCincinnati

Well-Known Member

GBGT350

Well-Known Member

GT Pony

Well-Known Member

GT Pony

Well-Known Member

GBGT350

Well-Known Member

MrCincinnati

Well-Known Member

mustang1

Well-Known Member

UnhandledException

Well-Known Member

Offboost

Well-Known Member

mustang1

Well-Known Member

TDC

Well-Known Member

SVTinAR

Well-Known Member

Offboost

Well-Known Member

mustang1

Well-Known Member