Silver Fun

255 F is highest I have seen mine. Coming off high speed driving then stopped @ light on off ramp.

Evil Buddha

The highest I have seen is 240+ at a DE track day.

daveak05

all sounds very well, although I'm having trouble understanding the logic being applied in "halving" and "halving" again, based on incremental oil temp readings.

Let's just say that if you track your car, the oil is goiing to suffer from shear and perhaps some high temp oxidation, although synthetics are much better at resisting oxidation.

It goes back to how you drive your car and how it relates to a need for more frequent oil changes. Servere service conditions, of which tracking would be one, mandate shorter service intervals. Just as do high dust conditions and extremely short driving distances, which doesn't allow the car to reach optimum operating temp.

daveak05

are affecting BMW's acceptable max temp limits, right? Wouldn't you say? I mean the NA RS4 engine should run relatively cooler than the turbo engine, in any case.

I like your new sig by the way. Is that an outline of Germany around your car, or the Nurburgring? : )

VerrÜckt

but the limits of what is safe for the oil and the engine internals are the same for N/A and forced induction engines.

BMW uses a VERY sophisticated engine management system on the 335i. They have the ability to monitor the oil temps and regulate the output of the car accordingly. Their research (which is in benefit to warranty claims) came up with the temperatures I listed. I can't help but think that they have a handle on what's ok and not ok for their engine.

As a comparison, GM runs Corvettes hard on the track until the oil reaches 300...then they come in for a cool down.

Oh, and thanks on the sig. A guy in the B5 forum (IBG) made it for me. It's way beyond anything I could do. The outline you see is the 'ring. An Autobahn sign is in the background. The pictures are from the 'ring.

bhvrdr

but in general tables have shown that popular oils out there are losing half their life at about 240 degrees and a 15K miles extended performance is cut down to about a 3500k mile oil when seeing consistent 260 degree temps. 280 degrees as stated by Don Istook means "extremely hot" and not something you want to see on a regular basis. It means dump that oil afterward. We dont rebuild these motors every month and if Don Istook says to beware of 280 degrees in a race motor than i'd want no part of it in my car. I think i'm going to mount a deal function oil pressure/oil temp guage before March.

VerrÜckt

which is more load than many cars will see in their entire life.

One of their cars even saw about 9,500 RPM due to a botched downshift.

They weren't rebuilding engines as often as you might think.

bhvrdr

component failure, but that isnt the place I would "start" worrying. I would worry long before component failure if trying to get 100K out of a motor. If seeing regular temps in the 250+ range I would start adding cooling and use a severe duty OCI. If seeing temps in the 280+ degree range I would dump the oil immediately and add cooling. Just my .02.

daveak05

Okay, I understand what you're saying about what's safe oil temps inside the engine, thanks.

My point was, whether the NA RS4 could also run at those limits, that BMW has probably had to adjust their limits(as far as engine control) up in consideration of the 335 and its 2 turbos. 2 turbos crammed in on one side of the engine, that's dumping a lot of heat there in a crammed space. The oil circulating thru the turbos and in the engine right around there is going to heat up quite a bit, I would think.

Not to say that this has any real bearing on what's safe/or not as determined by BMW, they know what they're doing. It was more just how they're dealing with higher temps due to the turbo(s).

bhvrdr

they would make for the turbo application is to add cooling rather than raise their acceptability of oil temps. I agree, that it will be interesting to see how successful they were at controlling temps as more people track those cars. I heard there were some bad initial impressions.