My Dad & his best friend all through the 70's and 80's always used either Kendall or Valvoline racing oil. They now normally use valvoline because Kendall seems to be hard to get. Now his friend doesn't change his own oil anymore & he has his mechanic do it with Kendall which he stocks and he said he instantly could tell the engine ran better. So it must be good stuff and he says he uses it whenever he can get a hold of it.