03 Accord rear main seal


Soon after having the oil changed in my 03 Accord EX V6 (155k miles with regular maintenance), I noticed oil spots in my garage. I have never had leaks from this car before. I checked the obvious places (filter, drain plug, oil pan gasket, fill cap, dipstick) and found no evidence of leaks. The cover plate and housing over the flywheel was covered in oil. I then had a trusted mechanic take a look at it and he told me that it was the rear main seal. It seems to me if the leak started shortly after an oil change that the two might be related. One other note…Catastrophic trasmission failure at 88k miles. Honda paid half the cost of the replacement. Any comments?


The only way the rear main seal leak could be related to the recent oil change is if was oil pan was overfilled, oil was spilled during the refill, or a very low viscosity oil was used. You might wipe the flywheel housing and cover and see if more leaks out. Otherwise, it is just ordinary wear and tear. If you have the invoice on the transmission R & R check to see if the rear main seal was replaced at that time. If not, you have gotten good service out of that seal. Maybe time for a drip pan.


The oil change and the rear main seal leak are not related. At 155K it’s certainly possible for a seal or two to start leaking, even on a Honda.


Catastrophic transmission Failure? What does that entail?

You have to remember, the transmission is attached to the engine, And if the transmission fails in a way where it puts undue stress on the crankshaft, it can damage the rear main seal. Now this may not show up right away. But can show up later on in the vehicles life.



Leaking oil tends to gravitate to the lowest point, usually under the flywheel. The leak could be the valve covers or the oil pressure sending unit. If its on the outside of the bellhousing (flywheel cover), I’d look at that pressure switch first.


before jumping to conclusions; did you by any chance have the oil change done at a quicky lube place. they can be notoriously messy. how long has the leak been there since the oil change, days?, months?
is it getting worse? is the oil level dropping?

make sure the engine isn’t overfilled, and clean up the area around the seal. Go as far as using an engine degreaser, and pressure hose to clean all the frame too.

let the car dry off, then look for the leak… clean cardboard slid under the car helps to pinpoint leaks (and saves the mess on the garage floor too)


It’s a rare car that doesn’t drip a little at 155K, ESPECIALLY Hondas. You might try using “high mileage oil”, which contains some seal conditioners…


You should consider checking the PCV valve. A clogged PCV will pressure up the crankcase and can even cause a new seal to leak.
Someone posted on this board a while back about a rear main seal and pan gasket job that was going to run about 700 dollars. The PCV was suggested and sure enough, problem solved.
They’re also cheap and easy.

As to your previous transmission failure it is my humble opinion that every time a transmission comes out of the car any seal between the engine and trans should be replaced; engine rear main seal, manual trans input shaft seal, auto trans front pump seal, etc.