When servicing the transmission, use only the lube oil of the recommended brand and type. Unlike most transmission systems, the automatic transmission does not feature a dipstick, and the level of the ATF can only be checked with the help of measurement while the specified temperature of the ATF must be maintained during the process. The check of the ATF level as well as the replacement of the ATF filter is described in the corresponding recommendations. The lifetime fluid is filled in the manual transmissions of E90 models and there are procedures to check and replace the manual transmission fluid in the corresponding documents.