I am running motorcycle specific synthetic oil from ams oil 20w/50, at least I will on the next oil change, right now I have 15w/50 mobil 1 in it.
Swampyjoe is right on the Quaker state etc. oils, any pennslvania crude oil will leave a sludge in the engine, they are all parrifin based oils. I saw that first hand when I worked at a service station while going thru high school. We had a customer that bought a new chevy, we did all of the oil changes on the car from new, at 35,000 miles his oil pump failed, we tore the engine down to replace it and there wasn't a bare space inside the valve cover for anything except for the lifters and push rods, everything else was covered with a waxy sludge.
Warn winch, Yamaha overfenders, Carlisle ACT tires, Yamaha fairing and windscreen, Garmin GPS V, hand and thumb warmers, County plow for winter,, 2005 Honda ST1300, 2005 Ford F150, 2007 Toyota Sienna.