RED LINE V-TWIN PRIMARY OILRED LINE V TWIN PRIMARY OIL For 1984 to present V Twin American motorcycle engines, including Milwaukee Eight, Evolution, Twin Cam and aftermarket engines of similar design Same fluid as their famous MTL gear oil Improves clutch operation while reducing wear and temperature Where most synthetics are too slippery for clutch operation, this friction balanced product is balanced to provide less slip, smoother operation and helps to apply more power in