Synthetic oil has several important advantages. Its a rounder molecule, thus is slippier. It doesn't degrade with heat as dino does. It clings to metal parts better. It flows better when cold. It runs cooler, it cleans better. Shall I go on? It costs more, but for a bike especially, it isn't expensive. And, if your bike doesn't use your engine oil for the clutches ( newer Sportsters example ), then Mobil1 auto oil is perfect and can save money over bike synthetics.
