I hope it is not seeping thru the rear main cap. I used the correct sealer there when I replaced the rear main....If it still leaks, that has to be it....
I like to put clear RTV behind the rear main seal before I install it in the cap and block, then let it harden a little before installing the cap... That way the rubbery RTV helps put pressure on the main seal to help keep it Gutenteight.... (good and tight) ---> That's what she said.... (in German)... :D