gsxr750

The main thing to be concerned with is really the temperature that oil actually starts to degrade or lose its lubrication and protection qualities. If you look up the specs on most oils the manufacturer will list them or you can call them for technical info on the oil you use.

Oil is actually a very good conductor of heat and will usually be a higher temp than your engines water coolant.

I called Mobile 1 tech line and they say normal engine oil starts to break down and lose its protection qualities and life as low as 140 F and synthetic oils will handle up to 220-250 F max. So if your engine oil is getting much hotter than your water temperature you probably want to install a bigger oil cooler to reduce the operating temperature of the engine.

One other simple cheap option would be to installer the lowest temperature thermostat possible or remove it completely, this would allow the engine to run a lot cooler, also turning on your heater will help to reduce engine temperture slightly.