I use the Stihl Green oil fully synthetic, at 30:1 when running the saws at full throttle cutting up big logs, no smoke, and the exhaust and plug are spotless, and a nice tan colour.
This is in the 440 and Dolmar and Shindaiwa.
Mate uses 50:1 "outboard" 2 stroke, blew his 066 up requiring new P/C. Now runs 40:1 with Stihl blue.
I tend to use the Stihl oil in everything from all the saws to the weedeater/hedgetrimmer and lawnmowers, although 40:1 in everything except the saws.
Local saw mechanic of 40+ years experience says any "quality" oil is good and interchangeable, but warns against 50:1 and has a saw graveyard he says is due to this 50:1.
I've used Husqvarna, Echo and Stihl oils for years, but really like the new green Stihl oil...even at $30 a litre here.