Oil Cooler
An oil cooler is functionally similar to a radiator, cooling engine oil rather than coolant. Engine oil is circulated through the inside of the oil cooler, while air passes through the fins on the outside, exchanging heat from the oil to the air, and lowering the oil temperature before it's returned to the engine (directly or the pan).
On the Z32
Twin Turbo model Z32s included a factory oil cooler. It used a very rudimentary and basic implementation, and many enthusiasts upgrade them to larger units with more efficient plumbing.
The TT's oil tree includes a port for the oil cooler's feed hose. A small portion of engine oil is diverted to this feed, which cools the oil through the oil cooler, and then returns it to the engine's oil pan. Many aftermarket oil coolers are larger, and some kits feature sandwich adapters that open depending on oil temperature, send a larger amount of oil to the cooler, and directly back to the engine (rather than the oil pan).
