If the cork gasket had slipped out, I'd say you found the leak. If the seal has a problem, many things could affect the rate of leakage. How badly might the seal be damaged? Was it installed correctly? Did you use too much silicone or no silicone for anti-rotation holes? Too much silicone might block the drain path into the pan. The weight of the oil may come into play also. I'd say you could have just a small leak or a large leak depending on the above scenarios. One thing for sure, If the rear seal was leaking, you would probably have oil all over the place.
Big block? Small Block? Nope, It's a Pontiac Engine!
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