Heavy duty platinum gear oil this is the top of the line, a full synthetic, PAO lubricant formulated specifically to run in Harley Big-Twin transmissions. We combine the leading synthetic PAO base oils with the most advanced additive package available today, to delivers maximum performance right through high loads and extreme heat. Heavy duty platinum reduces drag, friction loss, wear. It also and extends gear life and provides exceptional temperature stability for easier, smoother shifting. A.p.I. Gl-1 rated. Dyed green.