My 1991 F-150 developed a rear main oil leak about 20+ years ago. It's not a heavy leak, so I bought a couple of those big drip pans, and just lived with it. A few years back, (maybe a bit longer than that), I switched from regular Mobil 1 10w40, to High Mileage Mobil 1 of the same weight.
I can say it has greatly reduced the leak. It has not eliminated it. But it most definitely leaks far less than it did before. So I'll continue to use the product. Since then I have read that it's not a bad idea to use these type of oils if you have a newer vehicle that gets low mileage due to infrequent use.
This i'm not sure about, so I'm hesitant to try it in my newer vehicles that get driven very little. Besides, neither one of them leak a drop. But I would like to keep the seals properly conditioned so they don't start leaking.