Well, as far as additives I took this approach. Go to well supplied automotive chemicals place.
They'll have a bunch of oil stop burn products. Take each one, flip it upside down and see which bubble takes the longest to get to the top. That one is my choice. LOL.
In the old 77 Mustang II I had Gunk Stop Burn crap dropped oil consumption from 2qrts/week to 1 quart a month. After that, it began to lose effectiveness, I'd have to put in another bottle every couple months. I think it just leaked the crap onto the pavement.
