The "best" is very subjective, but I have used PPHM, M1HM, and VMLFS. For what it is worth, I prefer the Valvoline Maxlife FS. Bottom line for me is that it is spec'd for my cars/trucks and has been better at reducing, slowing or stopping leaks/weeping than the others in my cars that have needed that. I used it now for everything regardless of mileage.