Transmission Service Kit The transmission oil filter prevents harmful particulate matter from entering the transmission valve body and damaging valve body bores, solenoids, and other fluid passages. Foreign particles in valve body bores, solenoids, or passages will cause shifting issues. Some of these issues include delayed shifts, harsh shifts, or no gear engagement in extreme cases. Clogged filters can reduce fluid volume and flow in the transmission causing starvation of the transmission pump. This can be identified by an RPM-dependent whine from the transmission bell housing area. The transmission oil filter should be changed during any fluid service, and it is critical to replace the filter if major transmission components are replaced such as the torque converter, transmission pump, or transmission valve body. Transmission Service Kit Failure Symptoms Whining noise from the transmission pump Driveability and shift quality issues including harsh shifts, delayed shifts, or no gear engagement