requirement of oil to be labeled as synthetic?

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Aug 12, 2002
what's the requirement, or minimum requirement, for an oil to be labeled as synthetic these days? Let's say I buy brand x oil, and the bottle says either synthetic, full synthetic, or 100% synthetic. At worst, what do I know I am getting? Does the classification of synthetic refer only to base oil types (1..5)? or do additives, or something else, have any part in it? what about "synthetic blends"? what is the minimum requirement for an oil to meet the syn blend labelling?
If it says 100% synthetic, as do most of the Amsoil formulations, it means the carrier oil for the additives is also a synthetic, most likely some type of organic ester. If it says full synthetic or synthetic, the carrier oil is probably a petroleum base. Most synthetics are now using primarily GP III basestocks, with the exceptions of Amsoil, Mobil 1, RP and Redline ....It's very difficult to tell even looking at spec sheets what basestock blend is being used. You need to find the CAS #'s and look up what those mean to tell if it's PAO or Group III or Ester. Synthetic blends are basically unregulated and it's hard to tell what you're getting. The Schaeffers Supreme 7000 and the Amsoil 15w-40/PCO are probably the best ones I've seen with regards to synthetic content and long drain performance. Tooslick Dixie Synthetics
I guess the minimum requirement is that the oil maker/blender labels it as such. One would expect it to be Group III, Group IV or Group V base stock (or a combination of these). Additive package can vary greatly. At worst, you'll get an oil that at least meets the minimum specs and is most likely better than non-synthetic. Far as blends, "some" is required. Never seen any definition of "some", but it has been rumored over the years that it could be as little as 1-3 oz per qt. Does increase the profit margin, though!
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