[ZDan]

Originally Posted by gtengr

So basically you're not going to accept anything as evidence except the sort of testing that can only be afforded by an OEM.

The evidence I'm being provided with doesn't tell me anything I need to know! Oil cooler lowers track oil temps from ~272°F to ~250°F, OK, but what does that really mean? My guess is engine reliability/longevity is only *barely* affected for a street car that does occasional track days.

What you're seeing is likely the pressure drop from the cooler. That cooler oil is also doing a better job of cooling the bearings, and the mass flow rate would be higher at the lower temp.

Of course the pressure drop is due to the oil cooler. Yes, 250F oil should be "better" than 272F oil, but again no one is able to quantify how *much* better.
Regarding mass flow rate, it's gonna be very close to identical. I mean, how much do you really think the density of motor oil changes between 250F and 272F?! About 1% by my calcs... This is negligible compared to the temperature difference, that's the real "benefit". But again no one is able to quantify what that benefit is. If it's the difference between my engine living 200k miles vs. 180k miles (and I would guess that this is an exaggeration), I do not care...

The car's factory brakes/fluid can't even put the car into the situation we're examining, yet you're confident the owner's manual rec's are based on it.

The appropriateness of running factory street pads at the track is a completely different, totally unrelated subject!
Source is the Factory Service Manual, not the owner's manual. It makes no recommendations, it simply states that oil temperatures up to 279°F are "normal". I've already theorized on what that might mean.

You're also neglecting that the Mustang has a completely different oil system that could have enough capacity to maintain pressure throughout that range.

We have data on the FT86 that shows that it is indeed able to maintain the same oil pressure without an oil cooler as with an oil cooler, so we already know that we're not losing oil pressure by not running a cooler.

A lot of things go out the window in the track environment. You say uncharacterized as if there is actually a magic number threshold.

??? Nowhere do I say or suggest that. Of course there's no magic number threshold. My POINT actually relies on this fact. There's no step-function between 250F and 272F oil temps that implies that you MUST run an oil cooler.

Even an expert is not going to be able to tell you that 44.23 psi or whatever is the threshold beyond which accelerated wear is a guarantee.

Well we're at the same oil pressure with or without the oil cooler anyway, so I don't know what your point is here.

The person who took that data drew a different conclusion: "Now that we've seen how well it works on our car, we'll definitely be pushing everyone to run an oil cooler if you're tracking your car in the summer. As much as we love doing engine swaps for people, we'd rather not do it because someone spun a bearing from letting their oil degrade."

I disagree with his conclusion. No engine or oil expert would tell you that good synthetic oil "degrades" any significant amount from operating at 272°F.

To me, the logical assumption here is that the pump is unable to maintain pressure beyond that point. And if that's true, the situation is made worse by brushing off the observed pressure drop running at 270 F. Seems logical for the oiling system of a $25k new car.

Simple fact is that higher temperature oil has less viscosity, so for a given volume flow rate the pressure drops. With the oil cooler, the oil pressure drops the same amount but for a different reason: resistance in the oil cooler itself.

There is no one correct answer that applies to all people who track these cars. Endurance racing a track-only car, I'd run a cooler. For my usage, I still do not see any meaningful benefit to doing so.