Depends on what kind of motorcycle you ride.my .02
I agree 100% with everyone stating there is no reason not to use synthetic. these engines hold what 1 quart possibly 1.5 quarts?? for $10-$13/qt I can afford to use synthetic.
What I haven't seen is anyone asking about motorcycle oil.. IMO this is a better choice than automobile oil, because they remove the friction modifiers from it. Now I know some you probably believe this to be snake oil, but hear me out.
Firstly motorycle/atv engines have alot of aluminum, magnesium and some high performance stuff has impregnated ceramic impregnated and titanium. That being said In a motorcycle/atv the "oil" is doing double duty. It lubricates all the engine pieces, rods, crank, valve train, camshafts but it also needs to lubricate the transmission gears and the wet clutch. The forces, heat and general abuse that motorcycle oil gets is not the same as an automobile engine, where it just to lubricate some moving parts and flow around. The motorcycle oil gets crushed between steel and fiber plates in the clutch which is 100's of pound of force. Then it flies over into the transmission and is ground in between the teeth of the gearset.. Then gets pumped back through the system and runs over the valve train. Nowlook that may not mean anything, But motorcycles that are used in places that use snowblowers are run for a few months and put away. Just like our snow blowers, ridden hard and put away wet.
I dunno maybe I'm talking thru my butt since I didn't have my 2nd coffee yet.. I also haven't researched small engine oil, and might be the same as motorcycle oil.