Track or merely high performance use of the S62 engine in the BMW E39 M5 frequently poses the risk of higher oil temps, particularly if the under-plenum heat exchanger has been removed and blocked off (see our separately available HEX block off kit). Exactly where and how to add an external oil cooler of the right size and in the right location for the E39 M5, however, is far from obvious. Conventional locations such as behind the kidneys or in the foglight location are far from ideal from an airflow perspective not to mention the requirement that standard features of the E39 M5 have to be deleted or modified to make those locations work.
The best solution to date has been the Dinan S3 oil cooler that was available with its supercharged S3 kit for the E39 M5. That cooler was located immediately behind the radiator pointing at slight angle to the ground. Aerodynamically, this is the ideal location for the oil cooler, given the pressure gradient at that location and the Venturi effect. Of course, that oil cooler has been NLA for many years, and even when available presented a number of issues when installed, such as incompatibility with BMW brake ducts that many E39 M5 owners use.
Working with PWR, the premier manufacturer of race and high performance oil coolers, Partee Racing has developed an double-pass oil cooler with over 378 cubic inches of volumetric capacity (over 1.3 liters of actual capacity) and a set of custom stainless steel brackets that locate the cooler in the ideal location, but still permit use of the factory brake ducts and better protect the cooler from road damage. With AN-10 male fittings on the driver's side, hoses in and out of the cooler can be routed easily to the factory oil filter housing (or the "Gulf" version of that housing) and the engine, with plenty of locations for an external thermostat if desired. Given PWR's industry leading fin/tube design, we believe this is far and away the best oil cooler setup for the E39 M5.
Currently offered as just the cooler and brackets and intended for use with the Gulf oil filter housing and its internal thermostat, we subsequently will offer complete kit with custom XRP HS-79 hoses, AN connections for the housing and the engine, and a plate-type thermostat.
Finally, please note that the location of this oil cooler DOES require a cutout in the factory belly pan to maximize airflow through the cooler. For those who don't want to go this route, Partee Racing has developed an aluminum belly pan replacement (one substantially lighter than the other aluminum belly pan currently on the market) that includes the requisite cutout for the oil cooler with a leading edge to both protect the oil cooler from and to increase the venturi effect. The Partee Racing belly pan is currently in production and will be available for purchase in 3-4 weeks.
