Meade,
Coolant temps and oil temps are linked, so please provide more info on your situation. When you oil temp gauge shows 250, what does your coolant temp gauge show?
I would check the accuracy of your sending unit and oil temp gauge by using a hand-held temp gauge that you insert in the dipstick. Since you have a Subi engine, you may be able to check oil temps using your OBDII port also.
Synthetic oil can withstand oil temps far higher than 250 without significant shearing, and dino oils are almost as good. How many miles on the oil in the engine and what weight? Synth or dino?
Many times, the most difficult part of the car "fix" is determining what is actually wrong. Describing the symptom, i.e., hot oil, is not describing the problem. Installing an oil cooler will lower oil temps, but it would be nice to know first if your oil is really at 250F.
When you turn on your heater during hot oil events, you are actually installing a secondary radiator in your system, the heater core, so your coolant is able to shed additional heat, and your oil temp drops.
As others have stated, Carey is likely your best source for gold-plated info.