A rear main seal leak is very difficult to repair because reaching the rear main seal on an engine involves removing the transmission and, in most cases, the crank shaft. Mechanics often remove the entire motor from a vehicle to repair the rear main seal.
The rear main seal is one of the most-important seals in the engine because if it leaks, large amounts of oil can be lost very quickly. The rear main seal can leak due to improper installation, compression of the sealing material over time, and normal wear and tear. Reconditioning the rear main seal can help prolong its life and prevent oil leaks.