20W-50 Synthetic Motor Oil for Harley-Davidson, Classic Cars & Air-Cooled Engines
Built for air-cooled engines, older vehicles, & extreme temperature protection when engine wear prevention matters most.
Buy AMSOIL 20W-50 Synthetic Motor Oil // For Classic Engines & V-Twin Motorcycles
Designed for Harley-Davidson V-Twins, classic cars, & racing engines needing thick, high-pressure oil protection.
20W-50 is the thickest oil viscosity that we carry at Amsoil. With excellent wear protection, advanced detergents, and the ability to maintain high oil pressure, 20W-50 is a popular option for those running hot engines and needing additional protection. At Amsoil, we are proud to carry a variety of 20W-50 motor oils, including our Dominator Competition blend, Premium Protection and V-Twin proprietary formula.
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What makes AMSOIL's 20W-50 Motor Oil Different?
20W-50 motor oil is thicker and designed for engines that run hot or have wider tolerances, such as those in an air-cooled engine on a Harley. This is not a winter oil, but for those looking to keep their engine clean and reduce oil consumption in pre-1990 cars, trucks, or SUVs, 20W-50 might be a great option.
What kind of engines use 20W-50 motor oil?
This motor oil viscosity will never be used in a modern traditional engine. Instead, you will see 20W-50 used in classic and older cars from the 1960s through to the late 1980s, in air-cooled engines like classic VW Beetles, or in V-Twin engines on motorcycles. You may also see this oil type on race days, especially racing engines with loose tolerances that are looking to operate at high RPMs or in extreme temperatures.
The ideal use-case for 20W-50 synthetic motor oil.
The ideal use case for 20W-50 really depends on the car. However, you will most likely see a V-Twin Harley using this heavy of an oil, as well as classic cars from the 60s, 70s, and 80s that are looking to seal worn parts and prevent oil leaks.
What's Your Choice Of Ride?
We have an AMSOIL product for every vehicle - it's your ride, you decide.
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AMSOIL // Engineered For What You Drive & How You Drive
From daily drivers to diesel haulers, weekend toys to workhorse machines — every engine deserves oil that’s made to handle the way you use it. Share a few details with us, and we’ll match you with the premium AMSOIL products designed to protect your engine and boost performance where it counts.
Frequently Asked Questions
No Dumb Questions, Just Dry Dipsticks
Why do V-Twins use 20W-50?
V-Twins, specifically Harley-Davidson, use 20W-50 in their engines to primarily address the extreme heat management challenges of an air-cooled engine. Because Harley engines run hotter than other motorcycle engines, they require motor oil that stays thicker when hot. V-Twin engines also demand increased shear stability, as they often share oil between the engine and gearbox and require a high shear rating. Finally, because this engine type generally has larger gaps between components, a heavier, high-viscosity oil can fill those gaps and protect the engine from wear and damage.
When would you use Dominator Competition Diesel Motor Oil?
Dominator Competition Diesel Motor Oil is designed for high-horsepower modified diesel engines and offers wear protection to handle the high cylinder pressures and fuel dilution common in these heavy-duty trucks. If you are sled pulling, drag racing, or completing dyno runs, you should use this superior synthetic motor oil.
How do I know if my bike takes four or five quarts?
If you are not sure if your motorcycle takes four or five quarts, the best thing you can do is to check your owner’s manual. Generally, your oil capacity will be found under capacities or technical data in the manual. If you are unable to locate your manual, your next best option is to talk to an Independent Amsoil Dealer here in Northwest Ohio. Our team of motor oil experts know the answers to everything and can source the exact amount of oil that you will need to complete your motorcycle’s oil change.
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From coast to coast, AMSOIL Dealers are earning high marks from customers who know their engines. Whether it’s a daily driver in New York, a dirt bike in Arizona, or a diesel truck in Texas, real reviews are rolling in from every corner of the country — all praising the performance, protection, and reliability that AMSOIL delivers.