rear seal leak?

I bulit a 427, 454 block 3.76 crank 2 piece seal with rtv on the cap corners for my 65 pick-up. broke it in with break in oil no leaks. drained it and put in synthetic for flat lifters. now after running a little i have a very small drip on the bottom of the bellhousing. you think going back to reguler oil and running it somemore or just open it up and put a new seal in?

nope synthetic will make leaks. any thing with not the best for sealing gets worse. try going back to reg oil .it could not be the seal so much it is the crank finsh on the crank . you could pull the seal and try a flouroelastomer seal .but i would never run full synthetic in a older bbc for street use

X 2 what Pat said