Found this.... very interesting.

http://www.nightrider.com/biketech/oilinfo1.htm

Very Interesting Reading!!! Sure did shed some Light on the Subject!! :D

ShaZaam! I learned some stuff, too! Thank you!
Billy

Mobil's official position is that they use less polymers in all of their oil than anyone else - thus maintaining the viscocity after the polymers are dispersed/used up/broken down. In other words, better quality oil (at least dino). I have a good opinion of Mobil products. I will continue to service my sportster with TA-DA!! Valvoline 10w40 in winter and 20w50 in summer. Why? No... really... Why? Answers please - cause I got no idea - except it works well and it's what I've always used.