Oil cooolah

[Grady]

Originally Posted by Legend@wheels

which cooler for 160$?
the oem one?

Yes OEM one.

[gtengr]

Originally Posted by Vesartis

I work for an automotive OEM and I asked our thermal engineers about the oil temps I was seeing. They didn't seem very concerned, considering the fact that it was synthetic oil and only reaching those temperatures for a short time on track. Given their feedback, I decided that for me, I was more worried about an oil cooler failure than an engine failure.

I don't think anyone is concerned about the oil itself at those temps. The concern is about the pressure drop in the oil system and the influence on the bearing clearances.

Originally Posted by ZDan

Myself and #1 competitor in COMSCC time trials do not run oil coolers in our BRZs. 10-15 track days per year, track days consisting of four ~15 minute sessions. My car runs 270°F - 275°F while tracking according to '17 factory gauge.

FWIW here's how Ford characterizes oil temperatures in '18 Mustang Factory Service Manual:
38-60° C (100-140° F) (low)
61-137° C (142-279° F) (normal)
138-146° C (279-295° F) (warm)
147-160° C (297-320° F) (hot)

Some folks run +350 whp and their stock engines stay together too. I assume the recommendations in the factory manual exclude road course driving/extended high RPM use. I don't think you'll find many seasoned road course drivers who would consider 279-295 F oil to be just "warm."

[Vesartis]

Originally Posted by gtengr

I don't think anyone is concerned about the oil itself at those temps. The concern is about the pressure drop in the oil system and the influence on the bearing clearances.

Just trying to learn and get a better understanding, so definitely open to discussion. If the engineers I talked to aren't concerned about those temps and the effects of temp on viscosity, then I assume that means the FA20 is more sensitive to pressure drop than other engines. What isn't clear to me is what pressure represents? I though it was sort of a way of seeing an oils viscosity.

The thing that is missing from the equation in the discussions I have read is the actual flow of the oil. It seems like good pressure without good rate of flow wouldn't be good. The assumption is that an oil cooler lowers the temp, increasing the viscosity, and increasing oil pressure. But doesn't adding an oil cooler add resistance to the flow of oil? Is the change in flow small enough to be insignificant?

Merry Christmas everyone!

[churchx]

Vesartis: Pressure, or rather lack of it, means that there gets not enough oil pumped on bearings/friction surfaces, thus increasing wear or chance of failure.
IIRC there was chart or table with pressure vs temps, where with stock viscosity oils at high temps pressure was way below optimal to ensure reliable oiling.
Oil cooler addition to oil flow loop indeed will add some resistance, but gains from temps in check and less pressure fall off, outweigh slight illeffect of that extra resistance in worst cases/high temps scenarios. Also extra oil volume due extra lines & cooler imho are beneficial for in on high grip tires/lot of aero downforce/long speed sweepers where there might get oil starvation due high side-Gs.

[gtengr]

Originally Posted by Vesartis

What isn't clear to me is what pressure represents?

It represents the impact of the oil's density and viscosity changes on a car's oiling system. The stock oil pump moves oil by displacing a volume. Higher oil temp = less dense oil, which means less mass in each unit of volume that is displaced by the pump. Lower mass flow rate = less effective cooling of bearing surfaces, and that is independent of higher temp oil being less effective at cooling due to less temp difference between the oil and bearing surface. In addition, the lower viscosity at elevated temps reduces the strength of the oil film at the bearing and the efficiency of the oil pump. The adequacy of the oil film at the bearing is also dependent on supply pressure. You can judge density and viscosity changes from just the oil temp, but the oil pressure let's you know how your particular oiling system is reacting to it.

[ZDan]

Originally Posted by gtengr

I don't think anyone is concerned about the oil itself at those temps. The concern is about the pressure drop in the oil system and the influence on the bearing clearances.

Which is why you should consider running higher viscosity oil at higher temps. I run 5w30 at the track to bump oil pressure up closer to "normal".

I assume the recommendations in the factory manual exclude road course driving/extended high RPM use.

I wouldn't assume that, extended high-rpm use is probably the only way the engine would ever see temps up to 279F... I don't know precisely what their temperature ranges mean, but I would guess that "normal" means that the computers don't have to dial back much if anything to try to keep oil temperature down, "warm" probably means they start dialing back, and "hot" probably means limp-home mode. My guesses anyway...

I don't think you'll find many seasoned road course drivers who would consider 279-295 F oil to be just "warm."

I don't think you'll find many seasoned road course drivers who have much if any real knowledge regarding correlation between oil temperatures and engine reliability/longevity, and what a *real* safe max oil temperature is. Whereas a large manufacturer that sells and warrantees millions of cars/engines per year probably has a pretty good handle on that.

[gtengr]

Originally Posted by ZDan

I wouldn't assume that, extended high-rpm use is probably the only way the engine would ever see temps up to 279F...

The warranty probably excludes off road/closed course use. I don't see why the manual would cover it.

Originally Posted by ZDan

I don't think you'll find many seasoned road course drivers who have much if any real knowledge regarding correlation between oil temperatures and engine reliability/longevity, and what a *real* safe max oil temperature is.

Oil pressure gauges are just for looks?

[ZDan]

Originally Posted by gtengr

The warranty probably excludes off road/closed course use. I don't see why the manual would cover it.

I don't see why the manual would be anything other than *very conservative* when characterizing oil temperatures. Yet for them, 279°F is in the "normal" range. Quick search reveals that Z06 Corvettes would go into limp-mode at 320°F. I still have yet to see *any* evidence that running at 270-275F at the track is a problem for the FT86...

Oil pressure gauges are just for looks?

Oil pressure .neq. oil temperature. Low oil pressure is of course a way bigger problem than sorta high oil temperatures...
Should the driver have access to oil temperature and pressure? Of course, so he can see if/when things start to change (rising oil temp, falling oil pressure).
That doesn't mean he's an expert on the maximum safe oil temperature for the engine.

[churchx]

ZDan: many of those real large manufacturers 1) don't overengineer cars anymore like in past and don't care that much for it lasting a lot past warranty or initial 5 years, or rather do the opposite, for cutting costs & reduce material usage & rising efficiency remove any redundancy / excess materials for long life of car/engine/etc, 2) don't consider track abuse extra load & wear, in some cases deny warranty due track use and such

So while they have much more expertise/data/experience, big manufacturer words for generic owner only DD their car with limited abuse shouldn't be taken as final instance of truth either, no?

[gtengr]

Originally Posted by ZDan

I still have yet to see *any* evidence that running at 270-275F at the track is a problem for the FT86...

Did you read the thread were someone logged a bunch of oil pressure vs. temp data? Didn't look very promising to me for running at 275 F.

Originally Posted by ZDan

Oil pressure .neq. oil temperature. Low oil pressure is of course a way bigger problem than sorta high oil temperatures...

Then why pretend they're unrelated when talking about oil temp?

Originally Posted by ZDan

Should the driver have access to oil temperature and pressure? Of course, so he can see if/when things start to change (rising oil temp, falling oil pressure).
That doesn't mean he's an expert on the maximum safe oil temperature for the engine.

If the driver has an oil temp and pressure gauge, and has a good baseline, it doesn't take an expert to observe trends. How is someone who reads their gauges any less of an expert than someone who points to owner's manuals for other cars as a reference for operating temps on a road course. Can the brake pads/fluids on a 3700 lbs Mustang even take more than 1-2 laps?

Also, my point is not that catastrophe is imminent, but that extended high RPM use at 270 F can result in reduced service life. It's about being conservative to prolong engine life. Any car that spun a bearing after a lot of road course use in hot weather w/o a oil cooler might have been affected by this. You certainly can't say they weren't anymore than I can say they were.

[ZDan]

Originally Posted by churchx

ZDan: many of those real large manufacturers 1) don't overengineer cars anymore like in past

I don't agree. I think that now more than ever they have tremendous capacity to ensure vehicle and engine longevity for reasonable $$$, much much more so than in the past.

It is no more or less the case now than in the past that manufacturers will want to ensure they meet their life requirements for cars/engines at the minimum possible cost. The difference is that now they have MUCH greater knowledge about what is and what is not so important, have access to better materials, and have better manufacturing methods with tighter tolerances.

So while they have much more expertise/data/experience, big manufacturer words for generic owner only DD their car with limited abuse shouldn't be taken as final instance of truth either, no?

There is no one "truth", but if manufacturers are OK with 279°F oil temperatures and regard that as "normal", that means something to me. A lot more than well-meaning track-dogs who are used to running much lower more conservative oil temperatures, but based on a cozy feeling rather than any hard data.

It's all about managing RISK. *Actual* risk vs. *perceived* risk. I would bet that the *perceived* risk of running 270°F oil temps at the track in these cars is far far greater than the *actual* risk.
Meanwhile, the *perceived* risk of installing an oil cooler is probably more often UNDERestimated vs. the actual risks of adding additional potential leakage points, hoses/lines that may chafe on factory hardware, and an additional heat exchanger that may or may not meet OEM factory reliability/longevity/MTBF requirements.

Early in my career (aerospace engineer) I had to update/revise structural maintenance plans for large cargo aircraft and one major point was not to OVERdo inspections or repairs or pre-emptive measures as these operations can bring minor risks of their own. You can easily go *too far* with trying to be "conservative" and actually expose yourself to GREATER risks by trying to be "safe".

I'm not saying no one should get an oil cooler to track the car. A good cooler properly installed certainly won't hurt! I am saying that:
1. The outright *need* for an oil cooler has not been demonstrated
2. The risks associated with adding an oil cooler are non-zero (greatly increased potential for leaks, fires even!)
3. Going to 5w30 oil is a much easier way to get oil pressures back to more "normal" range while tracking at elevated oil temps

[finch1750]

I'll leave this here fwiw as well. It's old and may not be accurate of their current status, but worth considering imo

https://www.ft86club.com/forums/showthread.php?t=113722

[gtengr]

Originally Posted by ZDan

I'm not saying no one should get an oil cooler to track the car. A good cooler properly installed certainly won't hurt! I am saying that:
1. The outright *need* for an oil cooler has not been demonstrated
2. The risks associated with adding an oil cooler are non-zero (greatly increased potential for leaks, fires even!)
3. Going to 5w30 oil is a much easier way to get oil pressures back to more "normal" range while tracking at elevated oil temps

By way of 1 and 3, you're also saying oil pressure <45psi @ 7000 rpm is acceptable, because that's where it's going to be or worse at 270 F, even with 5w30.

[ZDan]

Originally Posted by gtengr

Did you read the thread were someone logged a bunch of oil pressure vs. temp data? Didn't look very promising to me for running at 275 F.

This thread https://www.ft86club.com/forums/showthread.php?t=91820 ? Of course oil viscosity and hence oil pressure will drop with rising oil temperature. I don't see any demonstrated correlation between oil temps and pressures vs. actual engine reliability, longevity, MTBF established here, though. What I *do* see is that oil pressure for 5w30 at ~270°F looks to be right at the same oil pressure with 0w20 at 220°F oil temp.
addendum: The *really* interesting thing to see is that with 5w30 oil, the pressure at ~272°F *without* an oil cooler is the same as the pressure at ~250°F *with* an oil cooler! (see plot at bottom of this post)

If the driver has an oil temp and pressure gauge, and has a good baseline, it doesn't take an expert to observe trends. How is someone who reads their gauges any less of an expert than someone who points to owner's manuals for other cars as a reference for operating temps on a road course.

I'm not saying I'm an expert. I am suggesting that Ford has metric f**k-tons more actual hard data and analysis regarding the ramifications of operating engines at these oil temperatures than the most experienced drivers have.

Also, my point is not that catastrophe is imminent, but that extended high RPM use at 270 F can result in reduced service life.

"Can" is a critical word here. I would say "may", or "might". Without contradicting this statment you could also say: "Extended high-rpm use at 270F might *not* result in reduced service life!"

For my usage, the practical concern is engine life for daily-driver usage at 20k miles per year plus ~12 track hours per year.
Assume for the moment that with zero track usage, expected engine life is 200k miles, or 10 years.
With the addition of 12 hours per year at 270F oil temps at high rpm, what do I think will happen to the expected 200k engine lifetime? I'd guess that it's something like 180k/9 years? Maybe...

It's about being conservative to prolong engine life.

But is it *really* being conservative to add multiple potential failure points that could result in leaks or even fires, to mitigate an unknown and uncharacterized risk of reduced engine life occasionally running higher oil temps? I don't think anyone on these forums can say.

Any car that spun a bearing after a lot of road course use in hot weather w/o a oil cooler might have been affected by this. You certainly can't say they weren't anymore than I can say they were.

I totally agree, neither of us can say.

By way of 1 and 3, you're also saying oil pressure <45psi @ 7000 rpm is acceptable, because that's where it's going to be or worse at 270 F, even with 5w30.

I'll take 45psi
From that other thread https://www.ft86club.com/forums/showthread.php?t=91820 :

Looks like running 5w30 with no oil cooler should give about 49psi at 7000rpm at 272°F. And running the same 5w30 *with* an oil cooler gives about the same 49psi at 7k at 250°F! So the pressure drop due to the oil cooler looks to be about the same as the pressure drop from running higher oil temperature without the cooler!

More than ever I'm convinced that oil coolers are not necessary to casually track these cars...