First, do a thorough cleanup of the engine to eliminate making a SWAG about where the leak is located. I've seen several rear oil seals replaced when the real culprit was a leaky side cover gasket or valve cover gasket near the back end of the engine. It's also possible, but very unlikely, that the core plug behind the camshaft can get loose and leak into the bell housing. Don't forget to inspect the fuel pump- - - -lots of them have a weep hole that can dribble crankcase oil and resemble a timing cover seal leak. Once you find the source of the leak- - - -fix it. Don't waste time and money on "mouse milk" additives!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!