I’m a little bit of a Porsche guy too so I spend a bit of time on those forums also and came across this chart posted by LN Engineering. If you own a Air or Watercooled flat six or even a Panamera or Cayenne you should know LN Engineering. The chart if by Lubrizol and even if you haven’t heard of them you probably use their products in your oil or fuel. They are a huge diviersified company, part of the Berkshire Hathaway group. They supply a lot of additives to the big oil companies as well as have a few aftermarket additives they sell separately.
