The rear engine seal on my 71 Super Bee is leaking. Is their any oil additive that I can add to the engine oil that would stop the leak. I don't want to pull the engine, because it is running fine.

They can be changed in the car. It's not the most
pleasant experience but it can be done.

Carquest has a good seal additive that does work in moderate cases. It is a bandaide but not a repair. I do not remember off hand the name but have used it and it worked. I am sure NAPA would have the same product. If you have a knowledgeable counter person they should know what it is.

You may want to try this first. Get some brake fluid and put a cap full in your oil. The brake fluid will cause the rubber seal to swell. It takes driving 2 to 3 hundred miles before the leak stops. Had a leaky tranny dip stick seal, put a little brake fluid on and it caused the 0-ring to seal. stopped leaking.