Slight recap- I switched from 15w40 dino to 10w30 Mobil Drive Clean SYN- Ool came out just about everywhere.

I took it to my mechanic who put the front seals in in September. He said they looked good, but he put new ones in anyway. The largest leak was form the intermediate shaft. He said that with 245K miles, the engine is slightly worn and crankcase pressure has built up. In addition, he stated that the car wasn't designed for this type of oil and the sealing/mating surfaces are not the same as newer engines. Because of all of these factors, he said to switch back to my Dino 20w50 (because I am in southern Texas and keep changing the oil at no more than 3000 mile intervals.

I changed my oil and put in 4 quarts of Castrol GTX 10W40 that I had in my garage... no leaks. I did notice that the Syn oil that I drained out had the consistency of water (seemed unusually thin). Maybe, I had a bad or mislabeled batch of oil- It came from Wal-mart in a 5 quart bottle- (not in single quart bottles).

Either way, as my old Texan Grandpa used to tell me- "Dance with them dat brung ya" I'm sticking with the Dino.
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1990 240- 245K- Original Owner-M-47, VX cam, IPD sprt springs, bilstiens, spt exh, euro lamps-turbo whls,- still slow but handles well- Near Houston