Urll get mixed responses,, some will say its fine others will say it leaves deposites in your engine which will contaminate the new oil, i used it but i did two oil changes, put it in warmed it up dumped it, new cheapish oil warmed it up dumped it with nothing added and then put my desent oil in! This was on a newly imported engine that had been sitting a while so i wanted to garrentee it was good! P.s i also changed my filters every time.