Originally Posted by bbhero
But... Edyvw was right though.... Look at your list in terms of "tougher" specs..
No, because Noack alone does not help you determine the base-oil type without knowing the base-oil viscosity.
For example take MB 229.5. While it has the toughest Noack spec -- 10% -- it can still be made and is still made from Group III. I bet what is inside those expensive bottles of the Mercedes - Benz Genuine Engine Oil is nothing but plain Group III.
The Mobil 1 FS 0W-40 is mostly GTL (about 3/4 GTL, 1/4 PAO) now, and it satisfies MB 229.5.
However, the Mobil 1 Extended Performance 0W-20 and Mobil 1 Annual Protection 0W-20 (and also the Mobil 1 Advanced Fuel Economy 0W-16) are fully PAO-based. Therefore, they are simply better oils in terms of resistance to oxidation, which is what these OEM specs are about, and which is what is important when you look at the IVD issue in GDI/TGDI engines, not to mention the turbocharger deposits. They are also a lot more expensive to make, as PAO costs perhaps twice as much as GTL.
OEM specs only ensure a minimum quality standard, just like ILSAC/API does. Results still vary greatly from oil to oil, and an oil subject to lower OEM standards could be of higher quality than an oil subjected higher OEM standards, depending on who makes it.