Originally Posted by Fahrer

What is the base stock used for some of these synthetics? If the they are polyol esters, how do they deal with seal swell? For example, Mobil 1 (and some other synthetics) is based on polyalphaolefins. PAOs by themselves can extract some plasticizers from some thermoset elastomers. Mobli adds some polyol ester to the mix to compensate for this. Are polyol ester based lubes compatible with the seals and elastomers used in a Porshce engine? Are they compatible with the piston coatings? Some elastomers are compatible with polyol esters but not PAOs and there are elastomers that are compatible with PAOs and not polyol esters. I use the same lubricant as the label attached to inside of my engine compartment lid - Mobil 1.