N54/N55 Fender-Mounted Air-to-Transmission Fluid Cooler Kit

The BMS N54/N55 Transmission Oil Cooler is designed to combat heat, the primary enemy of automatic transmissions, especially in higher-power applications. This kit replaces your vehicle's stock coolant-to-transmission fluid heat exchanger with a high-capacity, fender-mounted air-to-transmission fluid radiator. It installs on the driver-side fender, utilizing existing openings for ample airflow over the cooling core, resulting in significantly reduced transmission temperatures and extended transmission life. This upgrade is particularly recommended for any BMW E chassis automatic running larger than factory turbos. Installation is described as plug-and-play, with all mounting hardware, lines, and coolant caps included. An optional 165ºF (74ºC) thermostat is also available and recommended to maintain optimal fluid temperatures, preventing over-cooling and ensuring quicker warm-up times by bypassing the cooler until the minimum operating temperature is reached. Fitment is specified for automatic transmissions only and is compatible with both RHD and LHD vehicles. It is explicitly not compatible with manual transmissions. The kit is designed for various BMW E chassis models, including the 1 Series (2008-2013 E81, E82, E87 135i, and 2008-2013 E88 135i) and the 3 Series (2006-2011 E90 Sedan 335i/335ix, 2006-2013 E90 E91 Sedan/Touring 335d (M57 diesel), 2006-2011 E91 Touring 335i/335ix, 2011-2013 E92 Coupe 335is, 2007-2013 E92 Coupe 335i/335ix, and 2006-2013 E93 Convertible 335i/335ix).