Originally Posted by revhigh
I was looking at the standard OE oil ... which is probably pretty equivalent to commercial synthetic offerings like M1 and Pennzoil stuff.
OE is 100% hydrocracked petroleum, the same as Pennzoil Ultra.
XL is a blend of true synthetic and hydrocracked petroleum, the same as Pennzoil Platinum and Mobil 1
Signature Series is 100% true synthetic, something hard to find off the shelf these days.
Royal Purple and Mobil 1 Extended Performance are really the only two that are easy to find. Since Mobil 1 refuses to post the specs for NOACK Volatility on all spec sheets, we are questioning if even EP has VISOM hydrocracked petroleum in it.
Royal Purple also hides that spec from their base line lubricants. See where I am going with this?
NOACK Volatility is a specification that measures a lubricants tendency to evaporate/burn off at high temperatures. Anything over 9% volatility isn't a true synthetic. Mobil 1, and other big oil companies, know to hide this spec from trained eyes.