BEL-RAY Big Twin Transmission Oil is a multi-grade 4-stroke V-Twin transmission oil formulated for sliding contacts of gears in heavily loaded 4-stroke transmissions. Superior anti-wear Smooth shifting Reduces gear noise Quart . The Bel-Ray Big Twin Transmission Oil has an SAE viscosity of 85W-140. This viscosity has been proven through real-world studies to reduce gearbox noise, make shifting easier, and eliminate "clunking" when shifting compared to thinner viscosity oils. The high viscosity helps keep gear wear to a minimum and absorbs shocks when applying heavy acceleration loads to the gears. The Big Twin Transmission oil is the same viscosity as the Bel-Ray Gear Saver Hypoid Gear Oil 85W-140 that customers have used for many years in their V-Twin transmissions.