The leak had disappeared completely in a matter of days.
I have a 1987 Ford F150 with over 260k miles. It developed a rear main seal leak and not worth the money to have it replaced on a vehicle this old. Put the whole bottle of Lucas Oil Stop Leak in my next oil change and the leak had disappeared completely in a matter of days. The truck is also running smoother and the inline 6 engine sounds better than it did before.