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Originally Posted by gtengr
(Post 3166907)
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.
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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)
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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.
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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.
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Also, my point is not that catastrophe is imminent, but that extended high RPM use at 270 F can result in reduced service life.
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"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...
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It's about being conservative to prolong engine life.
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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.
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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.
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I totally agree, neither of us can say.
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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.
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I'll take 45psi :)
From that other thread
https://www.ft86club.com/forums/showthread.php?t=91820 :
http://i.imgur.com/m8H5JBA.jpg
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...