2. Oil Filter Leak. The oil filter is used to remove carbon and other impurities created by the combustion process. This filter is subject to oil pressure supplied by the oil pump and will leak if the filter is loose or the seal from the old oil filter is still on the block which can surface well after the oil change has been done.
What are the symptoms related to a bad rear main seal? An oil leak may be noted on the ground where the vehicle is parked. The leak will appear to be coming between the engine and the transmission, but over time can coat the underside of the car near the engine.
Rear Main Seal Replacement by Bill Schroeder The rear main seal leak among small block owners is a very common problem. From my poking aroung on the discussion boards I found out many owners with this do not fix it as they seem to know it's difficult to eliminate (some say a poor design).
These very expensive repairs are due to the fact that replacing the Main Bearing Oil Seals is extremely labor intensive and time consuming, and in the case of replacing of the 'Rear Bearing Oil Seal ' it requires the removal of the transmission, (or worse, of the entire engine on all front wheel drive models) - just to replace a $5-$10 oil seal!