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Just curious...
What is semi synthetic formulation,
50% Pure Crude oil / 50% Group III or
50% Pure Crude oil / 50% Group IV

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You won't find "Pure Crude Oil" in any motor oil (at least you hope not), Petroleum based yes, but it is refined.
As far as Group 3 or Group 4 under the "Synthetic" heading? You/We don't know, could be either, thanks to a Judge that ruled in favor of Castrol calling their "Syntec" line Synthetic. Syntec is a group 3, an oil that has been hydrocracked to a further degree than 'regular' oils. Molecularly changed, as CompSyn point out, and therefore the courts stated since the molecules are different, they have been 'synthesized'.

Since that decision, many "Synthetics" including Mobil1 are a group 3 or a blend of 3&4.

SemiSynthetics are , of course a blend of regular petro juice and 3 OR 4.

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