Originally posted by TooSlick:
PAO's are manmade, hydrocarbon based fluids that are derived from ethylene gas. All the Amsoil engine oils except their XL-7500 Series products are PAO/Ester based. The XL-7500 are Group III based oils.
The Series 2000/3000 oils are PAO/Ester blended basestocks with a different additive chemistry from the regular Amsoil 5w-30/10w-30/10w-40.