Make my own semi-synthetic blend. 1/3 Motul 710, 1/3 Poulan Synthetic (because the wife got cases of pump bottles on sale at $0.50 bottle
) and 1/3 2-stroke dino oil (whatever is on sale). Make up six or seven little bottles painted blue so I know what they are and blend with 2.5 gal of pump gas at a time for about 40:1 ratio (maybe 38:1 cause I fill the little bottles to the top).
Even with synthetic or syn blend I wanna see blue smoke or it ain't rich enough. If it won't smoke, pour it out and start again. Only way to tell if someone might have straight gassed a tank. Since we have a volunteer crew working with us, I gotta see smoke or I'll shut it down and have them re-fuel.