What you should do is call the oil manufactures and talk to their engineers.
The Nodwell track rig that appears in my tag line below has a 453 Detroit in it that gets very hot when traveling through miles of mud up to the front bumper. I have a separate oil temperature gauge on it.
I called and talked to the Mobile 1 engineers. They said the engine oil could handle 250F without any problems, BUT if it went up to 290F for more than five minutes, that it would ruin the oil and it should be changed. This was several years ago, but again, call and talk to the mfg's engineers.
Bill
