Synthetic Motorcycle Oil FAQS

YES. AMSOIL synthetic motor oils are compatible with other conventional and synthetic motor oils. Mixing AMSOIL motor oils with other oils, however, will shorten the oil’s life expectancy and reduce the performance benefits. AMSOIL does not support extended drain intervals where oils have been mixed. Mixing other oils with AMSOIL motor oils may also void the AMSOIL limited warranty.

If you’re happy with the performance of the oil in your dirt bike, ATV or UTV, continue to use it. However, AMSOIL Synthetic Dirt Bike Oil is specifically designed for dirt bikes and is our primary dirt-bike recommendation. The same holds for your ATV or UTV; however, AMSOIL Synthetic ATV/UTV Motor Oil is our primary recommendation for ATVs and UTVs.

Motor oil, whether synthetic or petroleum-based, consists of molecular chains of hydrogen and carbon atoms, referred to as hydrocarbons. Petroleum crude oil is a thick, highly flammable dark-brown or greenish liquid with high energy density. Many contaminating elements exist in this complex mixture of hydrocarbons, including sulfur, nitrogen, oxygen and metal components such as nickel or vanadium. Petroleum crude oil is the raw material used for a wide variety of petrochemicals, including solvents, fertilizers, plastics and lubricants.

The oil refining process separates the various types of molecules in the oil by weight, resulting in a concentrated batch suitable for manufacturing products such as gasoline, LPG, kerosene or lubricant base oils. The chemical composition of conventional motor oil can vary substantially depending on the raw crude oil refining process.

While petroleum base oils are refined, synthetic base oils are manufactured and can achieve a higher performance level. Synthetic oil is chemically engineered for a certain molecular composition with a tailored and uniform structure. Such fine-tuned control over the final molecular composition of synthetic oils is the key to their superior performance properties. Designing molecular structures in a planned and orderly fashion results in molecules, and end-products, that are far more stable than their refined petroleum counterparts.

YES. AMSOIL synthetic motorcycle oils meet JASO MA2 friction requirements for use in wet-clutch applications.

YES. In addition to withstanding extreme pressure, protecting against rust and withstanding high temperatures, motorcycle oils must be compatible with wet clutches. AMSOIL synthetic motorcycle oils are designed to meet the unique frictional requirements necessary for wet-clutch compatibility and provide maximum protection and performance in these applications.

If they’re happy with the performance of their current AMSOIL synthetic motor oil, they can continue to use it. However, AMSOIL 15W-50 Synthetic Metric Motorcycle Oil is made for riders who aren’t comfortable deviating from the manufacturer’s viscosity recommendation.

AMSOIL 10W-40 Synthetic Metric Motorcycle Oil contains a robust additive package designed for the extreme pressures and high temperatures common in motorcycle applications. Its high TBN retention also makes it the appropriate choice for extended drain intervals. In scooter applications, Formula 4-Stroke 10W-40 Synthetic Scooter Oil is the more economical choice.

NO. Shaft-drive applications normally call for a fluid meeting the API Gl-4 or GL-5 service classification. AMSOIL Synthetic Metric Motorcycle Oil is rated API GL-1 and is not suitable for these applications.

Not really. Powerful, V-twins generate intense heat, this is especially true in slow-moving rally or parade traffic. Air-cooled bikes rely on a stream of air flow over the cooling fins to keep the engine cool. Stop-and-go riding and extended idling on hot summer days can quickly cause the engine temperature to skyrocket. If the motor oil cannot withstand the intense heat and powerful mechanical action inside a V-twin engine, the oil loses viscosity. V-Twin powered motorcycles are well-suited for cruising and touring the open roads. These engines typically hold 4 to 5 quarts of oil.

Dual-sport and dirt bike operating conditions involve ample low-speed stress punctuated with periods of high revving. When racing, there’s frequent repetition between wide-open throttle on the straights and rapid acceleration through the corners. Throttling through jumps causes the rear tire to spin freely in the air, then create a heavy load on the engine when it contacts the ground. And trail riding requires lots of clutch and throttle manipulation to maneuver over and around obstacles.

Dirt bike engines are typically lightweight designs meant for performance. Any time you remove mass and increase power, you increase engine stress. The combination of high rpm and lighter materials creates the perfect scenario for engine failure if the motor oil fails to do its job.

Additionally, dirt bike pistons tend to have shorter piston skirts to reduce friction, which doesn’t help engine longevity. A shorter piston wants to rock inside the cylinder, which concentrates tremendous force on the tiny area where the piston skirt and cylinder wall contact. Only a microscopic oil film provides protection in this area, superior oil film strength is needed to help the engine survive.

On top of this, dirt bikes barely hold any oil, often only about one quart. That single quart of oil must fight wear, resist heat and prevent deposits.

As you can see, operating conditions between V-Twin powered bikes and dirt bikes are quite different, leading to the need of a engine oil formulated for the type of bike.

AMSOIL 20W-50 Synthetic Motorcycle Oil and SAE 60 Synthetic Motorcycle Oil are the most commonly recommended oils for Harley-Davidson applications. Check the AMSOIL Motorcycle Product Lookup for specific recommendations.

AMSOIL 10W-40 Synthetic Motorcycle Oil (MCF) contains a robust additive package designed for the extreme pressures and high temperatures common in motorcycle applications. Its high TBN retention also makes it the appropriate choice for extended drain intervals. In scooter applications, Formula 4-Stroke 10W-40 Synthetic Scooter Oil (ASO) is the more economical choice.

For the newer Big Twins, AMSOIL recommends 20W-50 Synthetic Motorcycle Oil (MCV) in the engine, transmission and primary chaincase. As secondary recommendations, Synthetic V-Twin Transmission Fluid (MVT) may be used in the transmission, and Synthetic V-Twin Primary Fluid (MVP) may be used in the primary chaincase. In older Harleys such as Knuckleheads, Panheads and Shovelheads, AMSOIL recommends SAE 60 Synthetic Motorcycle Oil (MCS).

AMSOIL recommends 20W-50 Synthetic Motorcycle Oil (MCV) for Harley-Davidson Sportster engines, transmissions and primary chaincases.

YES. AMSOIL 20W-40 Synthetic Motorcycle Oil meets the physical requirements outlined in the API SM oil specification.

NO. AMSOIL Synthetic Chaincase & Gear Oil does not have the correct viscosity for use in Harley-Davidson primary chaincases, and is not recommended for these applications. AMSOIL 20W-50 Synthetic Motorcycle Oil (MCV) is the primary recommendation for Harley- Davidson primary chaincases. The secondary recommendation is AMSOIL Synthetic V-Twin Primary Fluid (MVP).

AMSOIL recommends 20W-40 Synthetic V-Twin Motorcycle Oil (MVI) for all Victory and 2013 and newer Indian motorcycles, excluding the Scout which requires 15W-60 Synthetic V-Twin Motorcycle Oil (MSV).

AMSOIL synthetic motorcycle oils are engineered to provide outstanding protection for up to twice the manufacturer’s recommended change interval or one year, whichever comes first. Unless using an AMSOIL Ea Motorcycle Oil Filter, change the filter based on the manufacturer’s recommended interval. For Big Twin Harley-Davidson transmissions, follow the Harley-Davidson recommended drain interval for synthetic oil up to 20,000 miles or one year, whichever comes first.

Synthetic V-Twin Primary Fluid has the physical characteristics of an SAE 50 motor oil. This does not mean it can be used in engines - it is merely a universally understood reference to its viscosity. Do NOT use Synthetic V-Twin Primary Fluid in the engine or transmission.

Synthetic V-Twin Transmission Fluid has the physical characteristics of an 110-weight gear lube. Although it has the properties of a gear lube, it is NOT a specification-rated gear lube. Do NOT use Synthetic V-Twin Transmission Fluid in the engine or primary chaincase.

AMSOIL offers motorcycle oils in different viscosities to accommodate the differences between motorcycle models and manufacturers. Just as in automotive applications, motorcycle engines require specific oil viscosities for optimal performance and protection based on the components and tolerances in the engine.