Mobil 1 75w140 Synthetic Gear Lube 1 Quart

For a Harley transmission, you can use either Mobil 1™ V-Twin 20W-50 or a heavier, gear-specific lubricant like Mobil 1 Syn Gear Lube LS 75W-140. While some owners use the 20W-50 in all three holes (engine, transmission, primary), a dedicated gear oil for the transmission can provide smoother shifting and better protection under high stress. Always check your specific motorcycle's service manual for the manufacturer's official recommendation for your model and year.