The car it's self also plays a huge part, some cars have a much more efficient drive train than others. Some people don't do much maintenance and even the cars that have an efficient drive train will suffer due to bound up bearings. I have also seen guys that clean all grease out of bearings and run all metal shield bearings in the drive train and hubs and still not get 10 minutes with a super free drive train. LEAN her out, I really doubt there is an engine out there that's going to run for 10 minutes at 210 degrees. I don't own a temp gun, but I am sure 250+ is quite normal for me when tuned for max run time.