All the MAJOR players do a god job! I have always used synth!There is one exception however... about 5 months ago I posted " Died out on the road" . My '04 zx/50 is HEAVILY modified (gets about 39-45 mpg) and I ran out of oil 2t. I stopped at a local gas/ beer/ sunglasses shop, and picked up a 1/2 pint bottle of 2t oil w/ a pict. of a lawn mower on the bottle. ($3.25) . I continued to run approx 3-4 days, until my post...The end result was a hole in the top of the piston that was NOT visable from the top. I spent several $/days looking at EVERYTHING else. If you go back to that post it will show everything. I eventually decided to pull the engine to paint the scoot, and as long as it was out i figured I would pull the cyl. to heat it in the oven (so as to wrinkle paint it), and as long as the cyl was off i pulled the piston for safe storage, and there it was. From the bottom of the pist. you could see a dime size spot of brand new shiny aluminum, dead center. I tried to fill the piston w/ gas (upside down), and it came running out like a shower head. Bottom line is,l if you are running a stock scoot most oils will work- If you mod...KEEP YOUR DUCKS IN A ROW!!!