Furthermore, M-1 has always touted their "pours at temps. that cause other oils to be solid"...and hence, they're oils are 0-20, 0-30, 0-40. Hey, I'd like to see a 0-50 (the 5-50 is old school). Partly because PAO's have very good low temp. pour characteristics, and partly because Mobil oils are on the 'thin' side anyways. But, I think it's mostly a marketing thing. Certainly spured other 0-40's out there!