Red Line Oil For V-Twin Motorcycles

Made for power. Obviously. Red Line motorcycle and powersports lubricants are designed to resist the shearing action and keep the viscosity within the desired specification while providing superior wear protection.

Read more below or Contact Us to find out why Red Line Synthetic Oil is the best choice for your V-Twin Motorcycle.

Power, Protection, and Piece of Mind For Engines

The connection between Red Line and American V-Twin motorcycles goes back to the early ’80s. The past 30 years produced tremendous support for Red Line  from experts in the racing and road bike communities, including the AHDRA Drags, AMA dirt track and road racing, and the performance and cruising scenes at Daytona and Sturgis. Legendary V-Twin builders like Bill Werner and Kenny Tolbert, respected tuners like Hal’s Speed Shop, Dan Fitzmaurice’s Zippers outfit, NHRA Champs like Matt Smith and Byron Hines rely on Red Line to control wear, make power, and increase reliability.

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This photo illustrates the oil pump from a Twin Cam engine. You can see the wear on the g-rotor as well as in the oil pump body. This is better controlled by using Red Line’s 20W50 Motorcycle Oil with more antiwear and stable viscosity. If this pump fails, not only will oil flow stop but a chunk of metal will likely junk the rest of the engine.

The same principles apply to all of the popular bikes, from Panhead and Shovelhead, to Evos and the latest production bikes. The V-Twin challenge is obvious: air-cooled engines demand more from motor oil. What happens when you run lesser conventional oils, low-cost “synthetic” blends? You find excessive wear in the cam journals and lifters due to shortages of antiwear additives.

This is in addition to premature main bearing, rod bearing, and valve guide wear (leading to oil consumption).  Shorter valve spring life and lower spring tension due to high heat can be a result of low-cost base stocks. Lack of film strength also leads to excessive piston wear (including scuffing on the skirts). Lack of cleanliness causes carbon buildup in the ring lands. Combined with poor piston wear, you get lower ring seal and less power from your bike. Where the latest bikes feature EFI, most of the V-Twin market is carbureted—even when you nail the jetting, you’ll get more fuel dilution with a carbureted bike and that challenges the film strength of lesser products.

There are many benefits to running Red Line’s ester-based motorcycle oils. Unprecedented stability over a wide temperature range is due to an investment in only the best base stocks, a bountiful additive package of zinc, phosphorus, and motorcycle-compatible friction modifiers make it the ultimate protection for American V-Twins. High detergency levels combat the buildup of carbon that depletes ring seal. Decades of R&D have gone into this product, so that kind of detail cannot be summarized in a few simpleparagraphs. But, the best engine builders say it better than we can. Many times, the lack of wear in the parts tells the story for them.

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This photo shows the stock camshafts from a typical Twin Cam engine with 40,000 miles that was filled with the synthetic motor oil recommended by the manufacturer during scheduled maintenance at an authorized dealer. The dramatic wear on the lobes and a totally blue cam journal could be avoided with more antiwear and a more stable ester formula. Note that aftermarket cams will show the same wear and heat, but better oil solves these problems.

Rob Schopf of Hal’s Speed Shop says it best: “The engines we take apart after running Red Line motor oils simply don’t have problems. That’s why we recommend them.”

Credit Harley-Davidson® with major improvements in their latest engine designs, especially in terms of cam plate design. H-D engineered a solution that removed the bearing setup, a great improvement. They also equipped the newer 96-inch engines (07-09) with a revised oil pump that scavenges 22% more oil, feeds 8% more than the older engines stock engines, and produces 8% more volume.

“Time will tell in terms of wear on the new bikes,” Schopf says, but these revisions produce a nice reliability gain. Regardless, there’s still damage to be done by selecting motor oil by price rather than all-out performance.


That mostly depends on where you live. Our 20W60 Motorcycle Oil is likely required only in the hottest climates like Phoenix or Las Vegas, or with the wide engine clearances that come from Knuckle, Pan, or Shovelheads. We find that many customers looking to dampen valve train noise or seal leaky bores use our 20W50 Motorcycle Oil. Even with giant displacement, fantastic cylinder heads and an aggressive cam, our 20W50 holds up. After all, it holds its viscosity longer than the conventional and “synthetic” blends recommended by the major manufacturers.

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Notice that the cross hatch is almost worn away from an inferior oil’s collection of heat. The vertical marks here better show the only place where the ring is making good contact for a seal. Again, using a stable, ester-based oil that reduces heat buildup dramatically solves these problems. It controls piston and ring wear, too

Red Line’s 20W50 Motorcycle Oil is the correct product for use in aftermarket Big Twins like those from S&S and RevTech. The V-Rod® and other cruisers should run this product, too, as it has been formulated to be compatible with wet clutch configurations. Sportster® engines can use this product, too.

Here are a few tips for using other Red Line motor oils in your V-Twin. If you’re road racing or doing serious track days on a Buell®, try our 50WT Race Oil in your engine. You’ll get a bit more power from a slicker formula and more protection from the even-higher dose of antiwear additives. However, race oils feature dramatically less detergency, so you’ll have to change it more often.

Drag racing typically uses lower viscosities due to the low oil temperature that comes from shorter operating time. But, remember not to run extremely light oils on the street in your air-cooled engine!

Top Fuel racers like Doug Vancil don’t use our 70WT Nitro Motor Oil. Their bikes have dramatically smaller fuel pumps than a Top Fuel Dragster (for which that 70WT is designed), and it’s the fuel that wears out oil in drag racing—these teams run 50WT Race and 60WT Race blends depending on conditions. The same goes for teams running methanol.

A Better Idea Than Using Motor Oil in Your Transmission

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.

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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. For Sportster and Buell riders, Red Line has found Lightweight Shockproof (not shown) to be highly effective

Most experts and educated enthusiasts will tell you not to use a motor oil in all three compartments. 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. 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.

Why is it wrong to just use motor oil in the transmission? Simply put, motor oils contain additives specific to keeping contaminants in suspension. 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. It is safe to say that the problem with a compromise is that can’t do any one job really well.

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. Many Red Line fans started using this product in its automotive packaging, known as Heavy ShockProof® Gear Oil. The same product is now packaged as V-Twin Transmission Oil. By the way, it’s the same fluid used in the differential of the world’s best Top Fuel Dragsters.

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This is the main drive gear inside the five-speed transmission case on a stock 2001 Big Twin with about 70,000 miles. All of the power goes from the engine to the transmission and through to the rear wheel through this gear. 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. Much of this can be avoided by using Red Line V-Twin Transmission Oil with ShockProof.

Acting like liquid grease, this famous pink gear oil contains a suspension of solid microscopic particles as an extreme pressure agent—its unique solid dispersion cushions gear teeth to help prevent tooth wear and allows the use of lower viscosities. The fluid really isn’t that “Heavy,” as it classifies as a 90W gear oil. ShockProof gear oils also cling extremely well to metal, surely a big part of its noise dampening ability and wear control. The early stock V-Twin gearboxes are not exactly famous for their smooth shifting or quiet operation! That shifting clunk at the stoplight is gone after using our V-Twin Transmission oil, verified by the massive, unsolicited comments on the Internet’s most popular V-Twin sites.

However, the oil cannot prevent everything. Lugging your bike, especially a newer model, causes both noise and wear in the transmission. ShockProof gear oils can dampen noise and help gear life in the 2007-09 H-D® Cruise Drive 6-speed transmissions, for example, but its straight-cut 5th gear is quite noisy. Given that the 96-inch motor is judged by many to be under-powered when matched to its a relatively-tall 2.79:1 final drive ratio, the bike lugs in 6th yet makes all that gear noise in 5th  (helped but not prevented by V-Twin Trans Fluid). You shouldn’t have to go 90mph in 6th to avoid lugging, but is sure is fun!

Aftermarket gurus point out that this is improved in the latest bikes by Harley-Davidson’s move to a 103-inch engine and a more aggressive 2.87:1 final drive ratio. Harley fixed some of these issues in their latest iteration, as techs that have already taken them apart say it’s a great transmission.

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Here is that same Big Twin with 70,000 miles, a five-speed bike. See how the middle gear has wear down the center from the shifter forks? When the gear wears, it causes premature wear to the shift forks–they’re hurting each other. This is what causes the rough or missed shifts and our V-Twin Trans Oil helps to fight this, big time.

In the stock H-D 5-speed transmissions from 1980 to 2006, experts report that main drive bearing races have wear issues and were machined with wide clearances that combine with its heavy shifter drum for a clunky shift. Many of these noise, wear, and shifting issues can be helped by Red Line’s V-Twin Transmission Oil with ShockProof. Boxes from the late ‘90s feature an improved design thanks to a hollow shift drum that our gear oil can still improve. Aftermarket transmissions for Evos like Baker, Jim’s and others, have run very successfully on our ShockProof fluids. Many of these companies are customers.

Remember that ShockProof is designed for wet-sump applications only, you don’t want to run it through pumps, coolers, or filters. If you see how it is attracted to your gears, imagine how it could stick to the inside of a small hose that sees little pump pressure. Also, note that it’s the Heavy ShockProof/V-Twin viscosity (90W) that you want to run—we haven’t see the same level of benefits from going to our 80W Motorcycle Gear Oil with ShockProof®, Lightweight, or Superlight examples.

While many here at Red Line have been riding before it was cool (Tim Kerrigan Jr. is an AHDRA Pro Fuel Champion), we were quick to get on the Buell® bandwagon, dating back to the late ’90s. We like the Sportster® style engines and road racing style with an American flare. Technically, some of the engine and specifically transmission tips aren’t focused to this community so we will try to spread a bit of our knowledge here.

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The primary case on most American V-Twins is a separate compartment with an independent oil bath. It houses components like the clutch, primary chain, and starter ring gear. While most think about the primary case oil to control clutch slippage or chain/sprocket wear, many overlook the importance keeping the stator coil cool for longer life and reliability. Though you don’t see the rotor, it’s also in the bath

Our pals at Hal’s Speed Shop in New Berlin, Wisconsin ( enjoy these bikes, too. Hal’s have a lot of experience modifying them for drag racing, road racing, and street bikes, too. They have been a huge technical resource for Red Line over the years and back up our fantastic success with Lightweight ShockProof® (which closely replicates the slightly-lighter 80W Motorcycle Gear Oil with ShockProof®).

Rob Schopf from Hal’s reminds us that they prepped many 5-speeds in Buells and 883 for road racing, spotting accelerated wear on the main drive gear and the 5th gear on the countershaft. Lightweight ShockProof® eliminated this. Rob says, “If the fluid fixed this on the race bikes, it should keep the street-ridden bikes going for quite some time.” H-D improved the design when they went to a high-contact/ fine-tooth gear patch on later bikes (versus the older, wide teeth).

Hal’s reminds that the biggest performance gains comes from freeing up drag and resistance will free up power—ShockProof gear oils have the lowest coefficient of friction of anything we blend and more than most on the market. It’s one step of many details to make sure your bike runs at its best.

The latest Sportster examples (2006-2009) are much improved in the gearbox department, as they no longer puff oil out the breathers. They’d better be, as its hard to check the transmission wear in later bikes—the “trap door” which you used for access is no longer around, so you have to split the cases to see inside. Important note: Red Line does not recommend running V-Twin Transmission Oil or Heavy Shockproof in a Sportster/Buell transmission. Always remember to warm up your bike before draining or changing the gear oil, since that ensures that you get the most complete flush out of the transmission. 

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Owners of V-Rods or the liquid-cooled Buells (like the late, great 1126R) need to think about using the right motor oil to keep control heat, clutch wear and slippage, and gear wear. Unlike their traditional V-Twin cousins, these engines use one oil bath of 10W40, important to curtail wear on the small end of the rod and wrist pin.

The good news is that getting an American V-Twin’s primary case lubricated is easier than the engine or transmission, as its chain and clutch combination is served by Red Line’s MTL® gear oil. MTL features the balanced friction you would need to make a synchronized shift in a car—this lack of slipperiness is a great match to a wet clutch like in a V-Twin.

We now package this fluid as V-Twin Primary Case Oil, too. This product’s balanced friction and light viscosity provides excellent clutch operation with low drag for reduced power losses—the fluid is a 70W80 GL-4 gear oil, but it features the stable ester base stocks that ensure consistent film strength over a wide range of temperatures.

Simply put: Don’t lug your bike if you want to keep the primary chain and clutch in order. In 2007, the 96-inch engines started coming with a spring-loaded, automatic chain tensioner. When lugged, this design can combine with the bike’s tall gear ratio to ratchet the chain too tight, causing heat-soaked parts to wear—here, we hope you’ve switched to a our Primary Case fluid.

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