Leaky Cadillac

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Feb 12, 2004
Western Washington
My dad has a 1990 or so Cadillac Sedan DeVille, and it's started leaking a little oil. I understand that high mileage oils have additives to recondition seals and help with leaks. We've been using 15W-40 Pennzoil LL in this car for the last few years, does this stuff have any seal conditioning additives in it? I'm thinking about trying an A-RX treatment, but if that doesn't work, would a high mileage oil be better for stopping the leaks than the HDEO?
The Pennz. LL is not the same as the High Mileage oil. The LL is the dino version of a HDEO, and is a 15W-40. Try the Pennz. High Mileage stuff for a while and see what happens. Since you've been using the LL, I bet the engine is about as clean as your going to get it.
[Cool] I would suggest an Auto-RX treatment but keep in mind that it will only help on rotating seals. It will not work on things like valve cover and oil pan gaskets if that is the problem. Also Caddy engines are known for sprouting leaks (I used to work at a Cadillac dealer [Roll Eyes] ). If you find one that doesn't leak, that's the exception to the rule.
I guess the original plan wins then. Try A-RX, if it still leaks after the rinse phase is done, then switch to a high-mileage oil and see if that does anything... Thanks guys!
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