BMW E38 E39 E46 E82 E83 E85 E88 E90 E91 E92 E93 O-Ring Expansion Tank Oil Cooler O-Ring for Expansion Tank and Transmission Oil Cooler at Radiator (14.5 X 2.5 mm) Brand NEW part with full 1 year warranty. BMW part# 17 11 1 711 987, check fit below. Genuine BMW part, recently made: not been lying around.