In the first places Amsoil doesnt refine oil. They buy base oils from X company and additives from another and blend them.
In the second place the big boys like Chevron, Shell, and Mobil will not sell there best base oils and additives to Amsoil.
In other words Amsoil isnt among the best by a long shot.
This is not an accurate statement.
Amsoil is a blender, they do buy refined base oil and blend their proprietary additives to make a finished oil.
Valvoline also operates like this.
Refined oil is sold like a commodity product. The refined oil Exxon Mobil might sell to Valvoline, or Amsoil is the same product they use in their own oil.
There are different grades of synthetic base oil, grp 3, 4 and 5.
An oil blender can order any base oil they choose. Your cheaper synthetics are group 3 based, while the better ones are a larger percent group 4 or 5.
The additive package is what makes the oil.
The very best base oils,with a weak additive package, will still yeild a oil that doesn't last as long or protect as well.
Amsoil makes a product with more group 4 base stock and a stronger add pack than most competing oils.
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