I once had a circle track engine to work on, was built by Maurice Petty. It had the most amazing RTV like substance I have ever seen on anything holing the pan on and under the intake end rails.
I Swear...I thought about giving the engine back to the customer after working to get that pan off!! It was stronger than windshield sealer!! I have never ever seen anything like it before..If you glued a safe door shut with it you would Never be able to open it--Ever!
I inquired and was told that they lost a race one time over an oil leak and that he stated that would never happen again. I am here to tell you with the stuff they used there was NO need for pan bolts , and that is not a joke. We actually used a different oil pan as it was easier than getting that stuff off. I never found out exactly what it was --sort of silver looking