Mercury - Quicksilver 85W-140 Motorcycle Transmission Oil Heavy-Duty Gear Protection High-Viscosity Formula 8M0128385. Overview. There's a certain reassurance that comes from riding a big V-twin - that deep, rolling pulse, the steady pull, the sense that the machine underneath you was built to work hard. But those engines, especially the ones with separate gear cases, demand oil that can stand up to real heat, real load, and real miles. Quicksilver 85W-140 Motorcycle Transmission Oil delivers ex