Are all HM oils syn blend? Are there any HM oils that's easily found which are NOT a syn blend? As in conventional. I am not 100% sure but is Pennzoil a "conventional" HM oil? EDIT: NOPE. Looks like it's also a syn blend !!! So are there NO conventional HM oils at all? Valvoline ML, Castrol GTX, Mobil 1 HM, QS HM ... they all seem to be syn blend. I am specifically interested in the 5/20 and 5/30 varieties.