Behind The Speed: Oil Coolers

Oil does its best work within a specific temperature range. Too cold? Low flow problems. Too hot? Metal to metal game over. Cold engine startup is no time to get rev-happy and the hot end of the oil temperature spectrum is a danger zone of accelerated wear or outright engine destruction. Oil can run a little hotter than coolant but protection decays rapidly as temperatures climb. Enter the oil cooler. Factory-issue oil coolers do the job for factory-issue driving. Bumping up performance or towing heavy loads can not only create excessive heat in the engine but also down the powertrain line into transmissions, differentials and power steering.





Battered late-Eighties factory off-road heavy-duty oil cooling from Mitsubishi with plenty of room for improvement with a universal oil cooler like this fin and plate unit from B&M.

Engine Oil Control

Drivers of vintage Porsches and riders of air-cooled motorcycles already know that oil and air not only keep the engine cool but also prevent it from eating itself up. Consistent performance is an added bonus to longevity. The air-cooled VW crowd has long used external mount oil coolers to keep modified air-cooled flat-4 engines alive on Baja runs or slow uphill microbus crawls. Race cars bristle with oil coolers. The factory-issue oil cooler is making a comeback thanks in part to the great turbocharger resurgence. Modern production oil coolers generally fall into the air-to-oil variety or water-to-oil tube type coolers that live inside radiators.







Mustang turbo from Mishimoto shows off its coolers under the skin.