Quote:
Originally Posted by bmussatti
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Refers to the base oil used to make the motor oil.
Class 5 have base oils made of Poly-ol-esters. These are used in jet engine lube etc.
Class 4 are base oils made of Poly-ol-alephins. Also very good but one step below.
Class 3 are made of hydrocracked petroleum oils. Called synthetic by some, but not in Europe.
I don't vouch for my spelling the above chemicals correctly.