Well, I made it back out to the track for the first time since installing my STETT stage 2 oil cooler. I was one of the unlucky ones that didn't even have the factory cooler installed. I'm happy to report that oil temps never hit more than around 250 or so, and the car was super strong all day. Ambient temps were around 80 degrees. It's amazing how quickly you can improve on a track when you're not worrying about how many laps you have left until you hit limp mode! I got faster all day and was able to finish every session with no problem.
As far as daily driving goes, my oil temps now hover between 210 and 220 on my 30 mile daily commute. Prior to installing the STETT cooler, oil temps were normally around 235. I'm very happy with it. Ironically, I justified the purchase with my wife by telling her it would help protect the hot running 335i and extend the life of the motor. The truth is, I will now be able to drive much harder and deal out a sustained torture to the car over longer periods of time!
This track was an absolute blast. Here's a video from my last session. The rear-facing camera angle turned out great because you can really see the elevation changes on the hilly course (and watch me putting distance on some P cars).