Mercury - Quicksilver 10W-40 Full Synthetic Motorcycle Oil Motorcycle Oil Full Synthetic 8M0058915. Overview. There's a familiar calm that settles in when you know your engine is protected - not just on the days you're riding hard, but on the ones when the bike sits waiting for the next open stretch of road. Motorcycles live a different kind of life: high revs, tight tolerances, and bursts of heat that test every inch of the engine. That's why the oil you choose matters so much. Quicksilver 10W-