Originally Posted by slaterny
Be no longer confused. Do not know your engine too well, but later models than 1990 in general use a one piece oil seal. To replace; the gear box, flywheel/driveplate will have to come off to get access to the seal. Anticipate 2 days work all together. This if you are certain it is the oil seal and not the gasket. Or leak from the tranny. I would say $250 not a bad price. Get it fixed.
Switching from "normal" to synthetic oil. After any engine have been running for some time, lube oil will carbonize on surfaces and give a "perfect" tolerance (fit). Switching to synthetic will clean the engine. In other words you will loose the perfect fit, and you will have leaks. These leaks may disappear after a while as the new oil starts the same carbonizing process. But in your case, I would not count on it. Just because oil does not easily carbonize at either end of the crankshaft (if at all). We, that open up engines from time to time, can easily see if an engine has been running on "normal" or synthetic oil. It is quite a difference. My GC has been running 110K since day one on synthetic, I will not take the chance on switching to "normal" oil.
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