The same product is now packaged as V-Twin Transmission Oil. Many Red Line fans started using this product in its automotive packaging, known as Heavy ShockProof® Gear Oil. We are very proud of our motor oils, but Red Line's unique product known as "ShockProof" is truly a game-changer in terms of its effectiveness in a V-Twin transmission. It is safe to say that the problem with a compromise is that can't do any one job really well. Since transmissions don't have to deal with the byproducts of an internal combustion engine, wouldn’t you select gear oil with chemistry that is optimized for the conditions? The same goes for the primary case. Why is it wrong to just use motor oil in the transmission? Simply put, motor oils contain additives specific to keeping contaminants in suspension. Much of this can be avoided by using Red Line V-Twin Transmission Oil with ShockProof. Here you see blue - the sign of high heat - on the gear and wear in the center of the teeth-this bike has been running Syn 3. All of the power goes from the engine to the transmission and through to the rear wheel through this gear. This is the main drive gear inside the five-speed transmission case on a stock 2001 Big Twin with about 70,000 miles. Using a higher-quality, fully-synthetic 20W50 motor oil, a proper synthetic gear oil for the transmission, and a specific synthetic primary case gear oil optimized for the clutch and chain makes more sense for most motorcyclists looking to protect their investment and enjoy these bikes to the fullest. Just because the dealership can manage its inventory more easily with one oil type from the factory doesn't make this one product the best choice for your bike. Most experts and educated enthusiasts will tell you not to use a motor oil in all three compartments. Lubricants are a huge topic of debate in the V-Twin world, often focused on a simple question, "Is it the best way to follow the dealer and put a motor oil in my engine, transmission, and primary case, when I could get the correct product for each application?" After all, most American V-Twins are unique in that the engine, transmission, and clutch are lubricated through three separate systems. For Sportster and Buell riders, Red Line has found Lightweight Shockproof (not shown) to be highly effective. Red Line® V-Twin Transmission Oil With Shockproof is available in quarts only.Three of the most popular Red Line products for V-Twin motorcycles include V-Twin Primary Case Oil, Motorcycle 80W Gear Oil with Shockproof and V-Twin Transmission Oil with Shockproof. This product dampens transmission noise (reducing the notorious shifting “clunk” found in these gearboxes), dramatically reduces temperature, provides thicker oil films between gear teeth and completely resists throw-off. Red Line® V-Twin Transmission Oil With Shockproof is by far the best transmission oil you can buy for use in Big Twin 4, 5 or 6 speed street bikes – you’ll immediately notice smoother shifting and quieter operation! V-Twin Transmission Oil with ShockProof® provides unequalled protection for both stock and aftermarket American V-Twin transmissions. Red Lines’® racing heritage is reflected in all of their products…you’ll see more Red Line® products at the track than any other lubricant manufacturer for all of these reasons. Red Line’s transmission lubricants enhance smooth shifting, lower operating temperatures and reduce transmission noise. This defines Red Line® motor oil as a superior product for air-cooled engines, the heart of all American motorcycles. The thermal stability, film strength and reduced parasitic drag found in Red Line engine oil all contribute to lower operating temperatures, increased engine life and more power. Red Line® engine and transmission lubricants have long been the choice of racers and knowledgeable engine builders.