I've got to interject here...a leaner oil mixture IS NOT better for the engine! Its better for your wallet cause you don't have to use as much. The late Gordon Jennings, a renown 2 stroke guru did a dyno test and found that engines made MORE HP up to 8:1 ratio before it got near impossible to keep running at low RPM. Heres why:
More lubrication, less friction.
Thicker mixture, better ring seal.
Higher BTU burn then gasoline.
More interesting information located here:
http://www.planetsand.com/forums/ubb...page/0/fpart/1
If you read through that thread, you will also discover that although some synthetic oils like Amsoil, Klotz, etc have a better lubricity in tests, that the refined castor oils (Blue Marble, 927, blendzall, etc) leave a residue after they have been burnt that further lubricates things (think of something similar to graphite) that the synthetic oils do not have.