What is the reason for oil coolers?

Question

I know turbo engines have them cause of the extra heat.

My engine was used in a lot of suvs, trucks and large cars but in the sports cars they didnt have an oil cooler instead theres just an oil cooler by pass.

What would this be?

Answer 1

Keep the engine cool  for towing reasons.

Answer 2

Weight  of the vehicle determines the amount of load on the engine. A sports car is most likely to be lighter than a truck or an suv. So the manufacturer probably did not feel the need to use a oil cooler for that wehicle since the loads on the engine is much less and the oil does not heat up as much under normal driving. I would personally prefer to have the oil cooler though (in any kind of vehicle) because cooler running oil lasts quite a bit longer than oil that is not cooled. Regular oil starts turning black around 390 degree celcius and a fully synthetic oil such as Mobil 1 will stand temperatures up to 700 degrees celcius without turning black. As the oil gets darker, lubricating properties goes down.