I know you don't want to hear it, but use the cheapest name brand oil you can find and save up to have the seals replaced. You have a lot of miles and you've tried additives and such, so, I don't think anything can cure it other than new seals. I've owned quite a few vehicles with bad seals and the only thing that stopped it was replacement.
Try SuperTech HM oil if you want to try one, but replacement is the inevitable thing that has to occur.
Try SuperTech HM oil if you want to try one, but replacement is the inevitable thing that has to occur.
