What's the best way to fix a rear main seal leak?

Answer 1

The "best" way of course, it to remove the transmission and replace the seal. There is no approved additive that will stop the leak. An old used car lot trick is to add 1 pint of brake fluid to your oil. The brake fluid causes the rubber seals in the engine to soften and swell. This "damage" to the seals can cause the rear main seal to stop leaking however, this process is "damaging" to the seals (all of them) and may cause other leaks/problems.

If you do decide to try the brake fluid, be sure and change your oil after the leak has stopped. (hint: if it hasn't stopped leaking after running the car for 30 minutes, it isn't going to)

Answer 2

The ONLY way to fix a rear main seal leak is to pull the oil pan, pull the rear main journal, clean everything absolutely perfectly, replace the seal, put a very small coat of gasket eliminator on the journal, and put it all back together. There is about 50 pounds of oil pressure on this point at all times when the engine is running, so no amount of crap you put in the oil will stop this leak. Be sure it's the rear main before beginning. It would stink to do all that work for nothing.

Answer 3

That depends on how bad the seal is. If the seal itself is torn then obvivously the best way is to fix it. If you cant see any noticeable tears in the seal then you can buy additives with sealants in them that help make the seal swell up to prevent leaks. Tho it may not work on the first try most times over a period of time I can help the leak and sometimes stop it all together.

Answer 4

Make sure the underlying problem is not excessive crankcase pressure forcing oil past the seal. All engines have to vent somehow, if the vent system is plugged, pressure develops in the crankcase forcing oil out of everywhere it can possibly excape. Clue: carefully remove oil filler cap while engine idles, if a rush of gasses escapes the vent isn't doing it's job.