Since most refer to vortex-buicks:
"Engine Cooling
An old adage states that one-third of the combustion heat goes into making power, one-third goes out the tail pipe, and one-third goes into the cooling system. Turbo cars try to make use of the heat going out the exhaust to spin the turbo when required.
The one-third that goes into the cooling system heats the oil and the coolant in the block. We need some heat in both to make the oil work properly and to minimize wear as well as enhance engine efficiency.
Most engineers seem to think that oil should be at least 180 degs in order to burn off condensation and allow the additives to properly clean. On the other hand, oil temperatures that rise much above 200 degs begin to contribute to thermal breakdown which shortens the life of the oil and its effectiveness as a lubricant. How high is safe? I would guess that the curve steepens greatly at 215-220 degs when it comes to oil life. Okay, we can change the oil more frequently, right? Yes, but.....
The but is that hot oil splashing on the bottoms of the pistons, etc. contributes to detonation. We do not want 250 deg oil heating up the piston surface and pushing our engine closer to the detonation limit that what it was when we tuned for maximum safe performance on a colder engine.
The factory oil cooler is often discarded after an engine rebuild and not replaced with an alternate cooler. Many seem to think that the only purpose of the cooler is to prevent coking in the turbo bearings after the engine is turned off by reducing oil temps. While this has some merit, the factory was also concerned about detonation and realized the need to make the engines as consistent as possible.
If you are not running an oil cooler, go buy the largest one you can find. I like the B&M style for durability. The new ones with the fan are expensive but can be more easily mounted without so much regard for external air flow. Keeping the oil in the 180-200 deg range will not only help preserve the engine life, but, will make the car easier to tune and improve consistency of performance."
