While the E46 M3 and E39 M5 come with a factory oil cooler, it was obviously not designed for high performance driving. Just a few minutes on the track quickly shows how inadequate the factory cooler is. Dangerously high oil temperatures can lead to serious damage to your engine and need to be addressed.CSF and Rogue Engineering teamed up to create an oil cooler that could stand up to the rigors of track use while still being a simple and straightforward installation. The new oil cooler is over 2 times larger than the factory unit with a volume of 243 cubic inches (vs the factory unit's 103 cubic inches). This allows for cool, consistent temperatures in the hottest of days driven at the very limit.The CSF x Rogue oil cooler uses a Bar & Plate construction (vs. tube and fin) in a top/bottom configuration. The Bar & Plate design makes the cooler much more robust and able to take abuse from debris hitting it at high speeds on the road or track. The cooler uses extruded end tanks which means it is a much stronger design than simple bent aluminum sheet construction found on the oem unit. The cooler is a bolt on design for the factory radiator or the CSF High-Performance Radiators (E46 M3 - CSF #7058 / E39 M5 - #7064) and uses the factory oil cooler lines.