On several synthetic lubricant products (that I know for sure use PAOs and not GroupIII/Dino oils), it says on the back: CAUTION: CONTAINS SYNTHETIC LUBRICANTS. CAN CAUSE SKIN DISORDERS or something to that extent On almost ALL dino oils, it says: CAUTION: PROLONGED EXPOSURE TO USED MOTOR OIL blah blah Now on Mercon-V, it says: "Contains Petroleum and synthetic lubricants. can cause skin disorders" THis is true, Mercon-V is a synthetic blend. Now why doesn't the new SuperSyn Mobil 1 have a caution regarding snythetic lubricants??? It just has the prolonged exposure to used motor oil cautionary statement. Castrol Syntec has the Prolonged Exposure statement as well. I know some people are EXTREMELY allergic to synthetic lubricants (real synthetics).