switched to mobil 1 now the rear main leaks like a bitch

[gadget73]

My Mark VII was switched to synthetic oil at 180k. I replaced the original valve cover gaskets at 225k and they weren't leaking very much. The intake, oil pan, and rear main seals are original. The front seal I did when I replaced the timing set, but it was not leaking. I lose less than half a quart every 3000 miles and it doesn't leave any puddles, so I don't fully subscribe to the notion that going synthetic automatically creates leaks. If the motor was sludgey inside, then the synthetic oil will remove it and make bad gaskets more obvious though. The fact that it leaks now probably says more about past oil change frequency and oil quality than anything else. Its 22 years old, leaks are expected.

And second the thought that the intake and valve cover gaskets are likely your problem, along with a clogged PCV system. The rear main seals don't go bad as often as ancient cork gaskets do and nobody changes the pcv screens.

[sly]

Engine restore is a crock of shit.

every time I hear this... I point out a few smoking oil burning turds I've had the displeasure of fogging up the highway with. 500 miles after loading up a can of engine restorer and the smoking stopped. You do have to remember NOT to use engine gunk cleaners after that or you'll strip away all the engine restorer. Plain oil or you'll turn back into the mosquito truck.

one was an 89 toyota carolla with a 2bbl carbed 4 banger. The other is my 93 Vic.

[91waggin]

Always stay with dino oil on these older motors.

Have almost 200k on mine with synthetic since I got it. It leaked when I started, but I fixed them.

[rick99601]

my pcv isnt clogged.

[Deermann]

I changed my 1986 Mustang (5.0, 100K) also to full synthetic and it leaked for about a month. Then it stopped leaking.