bit high but I was pushing the car hard. Anyone else ever see temps that high?

B5 S4 guys are seening 250+F on the street in there cars with the stock coolers.

tests, how long has it been since your last oil change?

From what I've noticed with using the Mobil 1 is that average oil temps continue to trend higher with time from when the oil was changed & the number of miles on there.

this is assuming a quality synthetic. The oil isn't going to start to "break down" until 300+.

I'm not an oil expert, perhaps Scott can shed some light on the subject. :-)

Anyway, BMW's 335i doesn't start taking actions to reduce oil temperature until after 300F has been reached.

Verr is correct. The oil will thin significantly up at 300F. It will break down when the temperatures in hotspots get as high as the oil flashpoint. You normally want to have some room over the average oil temperature. Most oils, if changed on the 2500 mile schedule you are using are seeing flashpoint up around 310-330F. This means that near that temperature the oil will begin to vaporize. At 270F, you probably have 30-40F of head room. If you find that you're starting to burn more oil during racing, then you're most likely seeing spot temperatures in the engine approaching the oil flash.


You might try the Pennzoil Platinum Euro 5W-40. We finally got an oil analysis back on it and it's holding up pretty good. It seems to recover nicely from fuel dilution. If you want the best engine protection for your autocrossing, I'd have you change to the oil I'm using right now. It's made by renewable lubricants, but it's a straight 40W heavy duty synthetic that is built for racing. (It also has the same characteristics of a 10W-40 oil, which will be great all year round in your redneck of the woods.) It has an extremely high starting flashpoint of around 480F, whereas most oils are around 400F. This will give you quite a bit of head room when racing, and will not loose viscosity at high temps. Drop me a line if your interested.

<center><img src="http://www.nogaroblue.com/cars/bmwoiltempwarning.jpg"></center><p>They start reducing power at 298*F.