The ideal operating range is 200 to 230 degrees F (sump temp). At these temperatures the oil is working efficiently to produce the best power, economy and release of combustion by-products. If the oil is too cool, these by-products are absorbed into the oil, requiring more frequent changes to avoid bearing and bore damage. It is worth noting that keeping the oil at the correct temperature helps cool the engine; high oil temperatures will create higher water temperatures. This oil cooler has 10AN fittings. This is to allow you to use aeroquip stainless steel hoses.