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Published Jun. 25, 2019

Buying oil for a dirt bike is not the same as buying oil for your family car. You need a product that is designed especially for motorcycles and that can stand up to the punishment that a high-performance bike will exert on any lubricant. You also need to be clear about the job that you want it to do. Do you need to mix the oil with fuel? Is the oil for the transmission as well as the engine?

A dirt bike oil will have packages of specific additives that are designed to maintain the engine of your bike. There may be antifoam and surface-active additives, additives that clean or additives that help to dissipate heat. To help you make the right choice, check out our guide to the best 2-stroke and 4-stroke oils available.

The Best Dirt Bike Oil

This product is a versatile mineral oil that has been performance blended and can be used in all types of motorcycles as well as ATVs and side-by-side vehicles. You can even use it in scooters. It is a 4 stroke all-purpose oil that will give you stable clutch performance and will protect your engine from wear and tear.

This 4 stroke dirt bike oil has been produced by blending a top-quality mineral oil with ultra-clean additives. This produces an oil with outstanding anti-frictional properties and wet clutch performance. You can be sure that it meets or exceeds the requirements laid down for this type of oil by JASO MA, and it has achieved the highest certified rating that can be awarded to motorcycle engine oils. This is a genuine OEM Yamaha Product.

Key Features
  • Genuine OEM Yamaha Product.
  • Ultra-clean additives
  • Highest certified rating for engine oils
  • Suitable for all types of motorcycles as well as ATVs
Specification
  • Brand YamaLube All Purpose
  • Model LUB10W40AP04
  • Weight 7.5 pounds

Here we have a 2-cycle racing oil that is suitable for air-cooled and liquid-cooled engines. It is most suitable for engines that have an oil injection system (i.e. where no fuel/oil premix is needed), but it can also be mixed with gas up to a ratio of 50:1 because it has a solvent additive that  allows mixing with gas at all temperatures.

This 2 stroke dirt bike oil is a blend of mineral oil with polybutene and a special low ash additive. This gives it clean burn “smokeless” properties that prevent carbon deposits from forming on the piston rings, the skirt and the crown. It also prevents the exhaust port from blocking. This oil meets the requirements for “low smoke” oils.  

Key Features
  • 2-cycle racing oil
  • Most suitable for oil injection systems
  • Can be mixed with gas up to a ratio of 50:1
  • Special low ash additive
Specification
  • Brand Lucas Oil
  • Model 10115
  • Weight 8 pounds

This is a high-performance, totally synthetic racing oil. It is manufactured to suit 2-stroke engines and for premixing with gas. The synthetic base oil has a high film strength that gives your engine the best protection. You mix this 2 stroke motorcycle oil at a 32:1 mixture ratio.

The oil is clean-burning and will leave minimal carbon deposits in the engine. This also extends the life of your spark-plugs and reduces the amount of maintenance that you need to carry out on Honda Power Port systems. The formula of this 2 cycle oil also includes an additive that reduces friction to a minimum so you get a cooler run with maximum horsepower and a responsive throttle.

Key Features
  • Synthetic racing oil
  • Clean burning – minimal carbon deposits
  • Additive to reduce friction
  • Suitable for premixing with gasoline
Specification
  • Brand Honda
  • Model 08C35-AH21S01

This specialized motorcycle oil from Castrol will protect the engine, gearbox and clutch of your dirt bike. It can be used in 4-stroke motorcycles and V-twin motorcycles which are either fuel-injected or have a carburetor. Thanks to its unique Power Release Formula, it perfectly suits riders who love the exhilaration of a performance bike.

Tests have shown that this oil can deliver superb acceleration with just a touch of your throttle thanks to its rapid flow and its ability to minimize engine friction. It not only fully complies with but exceeds API SL and JASO MA-2 specifications.

Key Features
  • Suitable for 4-stroke motorcycles and V-twin motorcycles
  • Unique Power Release Formula
  • Delivers superb acceleration
  • Exceeds API SL and JASO MA-2 specifications
Specification
  • Brand Castrol
  • Model 6112
  • Weight 2 pounds

Castor 927 is a highly refined biodegradable oil made from a synthetic base with additives that work hard to reduce carbon and gum deposits. It also provides superb protection from rust and corrosion. A special additive will make sure that your power valves are clean and in good working order.

This product resists carbonization and vaporization so it carries on working when other oils would have stopped. This means that it provides outstanding protection for your cylinder walls and bearing journals even at very high temperatures. It can be used as a premix oil with leaded and unleaded gas. This oil is not suitable for bikes with oil injection systems. Take care when blending with race gasoline as it can separate.

Key Features
  • Highly refined biodegradable oil
  • Protection from rust and corrosion
  • Resists carbonization and vaporization
  • Not suitable for bikes with oil injection systems
Specification
  • Brand Maxima
  • Model 23964
  • Weight 4.2 pounds

Produced specifically for motorcycles, this multi-grade oil is stable and has advanced additives to improve performance. The oil has a petroleum base with anti-wear and anti-shear chemicals. It will maintain its stable viscosity stability in 4-stroke engines with integrated transmissions that are either air or water-cooled.  

The dirt bike engine oil includes anti-scuff additives that can handle extreme loads and cope with the peak temperatures and demands of a high-performance engine. It works in all weather and works hard to reduce friction as well as engine temperature so starting up your motorcycle is easier. It has been designed for wet clutches and reduces engine wear. The oil is Turbo certified and exceeds all the JASO-MA M/C 4T and API SG/CC specifications.

Key Features
  • Multi-grade oil
  • Meets the demands of a high-performance engine
  • Designed for wet clutches
  • Exceeds JASO-MA M/C 4T and API SG/CC specifications
Specification
  • Brand Maxima
  • Model 34901
  • Weight 1.8 pounds

If you are the proud owner of a Honda CR, CRD or TRX model, this is the racing transmission oil that you have been looking for. It offers ultra-high film strength as well as shear stability and therefore reduces the wear on the transmission.

The oil has a high thermal stability so it cuts down on foaming and there will be no premature breakdown of the oil. In addition to the base oil, there are anti-friction additives which give a smooth shifting and the drag is minimized as well as cutting down on power loss. Thanks to the anti-shear additives, the clutch life will be extended and slippage avoided.

Key Features
  • Suitable for Honda CR, CRD or TRX models
  • Ultra-high film strength
  • Anti-friction additives for smooth shifting
  • Extends clutch life and avoids slippage
Specification
  • Brand Honda
  • Model 08C35-A851M01
  • Weight 1.85 pounds

This is a 80w90 gear oil that has been specifically blended to suit the needs of a high performance motorcycle with a shaft drive. It contains high shear strength polymers so all of the gear surfaces get long-lasting protection. It can be used in all dirt bikes that have separate oil sumps for the clutch/transmission.

Any application where you need an API GL4 or a GL5 gear lubricant will suit this gear oil. It is for all dirt bikes that have hypoid/shaft drive gears.

Key Features
  • For high performance dirt bikes
  • High shear strength polymers
  • For bikes with hypoid/shaft drive gears
  • Long-lasting protection for all gear surfaces
Specification
  • Brand Maxima
  • Model 43901
  • Weight 1.6 pounds

This Maxima FFT oil is a synthetic polymer oil with a superior flow and that retains more contaminants than many other oils. It will resist water fogging and gas fogging wash out. You can rely on it to not migrate off the filter, and it will not dry out.

It contains a specialized solvent that does not interfere with the foam element or with the cement that is used to bond the filter together. It has a tacky formula that is suitable for all foam filters.

Key Features
  • Synthetic polymer oil
  • Resists water fogging
  • Tacky formula
  • Suitable for all foam filters
Specification
  • Brand Maxima
  • Model 60901
  • Weight 1.9 pounds

This Yamalube foam air filter oil works hard to maintain your foam air filter. The synthetic sticky formula will stop even small particles of dirt and dust from clogging up and damaging your filter. It also resists water.

It’s suitable for a EF1000iS Yamaha Inverter filter. It’s a petroleum-based oil that will keep water and dirt from entering the intake tract. It’s blue in color so you can see when the filter needs more oil. This oil is used by Factory Yamaha racing motorcycles.

Key Features
  • Foam air filter oil
  • Will stop even small particles of dirt
  • Bright blue so you know when more is needed
  • Used by Factory Yamaha racing motorcycles
Specification
  • Brand Yamaha
  • Model ACC-FOAMF-LT-ER
  • Weight 14.4 ounces

Best Dirt Bike Oil Buying Guide & FAQ

What to Look for in a Dirt Bike Oil

Buying oil for a dirt bike is not the same as buying for the family car. As well as brand and cost, there are some other features that you should look for. Always consult your manual to find out what oil is suitable for your dirt bike.

  • Motorcycle specific oil

You must buy an oil that is suitable for your dirt bike and these are not the same oils that are used in cars. Dirt bike oils should have additives that will help the oil to stand up to the huge demands a wet clutch, transmission and valve train will inflict on them. What’s more, a motorcycle has a flat tappet design that causes the oil viscosity to break down at a much faster rate than in a car.

  • Not a car oil!

The additives in dirt bike oils need to be very specific. The additives in car oils are very different. Car oils have additives which help to increase gas mileage. That’s great for a car, but in a motorcycle it will cause the wet clutch to slip. Motorcycle additive packages will make the oil able to withstand the added stresses of a motorcycle engine.

  • Antifoam and surface-active additives

In a motorcycle, the oil is being constantly aerated because of the leaning into corners and bouncing that takes place as you are riding. Therefore, motorcycle-specific oils contain chemicals that help to maintain lubrication under these very specific conditions.

  • Heat dissipater

Performance bikes, such as dirt bikes, need oil that contains an ester. This is a synthetic additive that helps with heat dissipation in a high-performance engine. Esters are the most effective racing oil additive. As the oil moves through the engine, it transfers heat to the outer parts of the engine where it is cooled by air or by a cooling system.

  • Cleaning agents

Some oils will be able to hold carbon particles in suspension and this stops carbon sludge from forming on internal engine parts.

  • Other additives

Solvents may be added to dirt bike oil to keep the engine clean. They break up deposits.  There may also be Viscosity Index improvers, corrosion inhibitors and buffers which will neutralize acid.

  • Synthetic or mineral?

Mostly, synthetic oil is the best choice, but not always! Manufacturers are now able to put together additive packages that make mineral oils perform just as well as the lower quality synthetic oils.

Enduro bike rider

2-stroke Oil Vs. 4-stroke Oil

There are two types of gas-powered combustion engines and they are the 2-stroke and the 4-stroke engine. The names indicate how they operate. Every engine works by combusting (burning) a mixture of gas and air and the products of combustion are eliminated through the exhaust.

In a 2-stroke engine, the combustion and exhaust cycle takes place within two strokes of the piston but in a 4-stroke engine it takes place over four strokes of the piston. The mechanics are simpler in a 2-stroke engine but the 4-stroke engine is more widely used. It is more efficient because no fuel is wasted in the intake cycle. These engines are, however, up to 50 % heavier.

In terms of engine oil, it is important that you use the correct oil for your engine because the two types of engine use oil in different ways. A 2-stroke engine uses a mixture of oil and fuel at anything from a 50:1 ratio to 20:1 ratio. In these engines, the oil application is reliable, but the fuel modification is greater. In a 4-stroke engine, you fill it with normal gas and the oil is injected from a separate reservoir.

Always check the specification of the oil you are buying. Some can only be used with oil injection systems but others can also be mixed with gas.

Difference Between Engine, Gear & Air Filter Oil

Oil is used in several different areas of a motorcycle. You will need oil for the engine, the gears (or transmission) and for the air filter. Some dirt bikes use the same oil for both engine and gearbox and this a uniquely formulated oil with dedicated technology.

Engine oil

Engine oil is a base oil with added chemicals such as anti-wear additives, detergents, dispersants and possibly viscosity index improvers. The function of engine oil is to lubricate the moving parts of the engine. It does this by forming a layer between moving parts and reducing friction and wear and tear of metal components. It also cleans the engine from sludge and neutralizes acids in the fuel. It also helps to seal the piston rings and cool the engine by transmitting heat away from the moving parts.

Most engine oils will contain chemicals to inhibit corrosion and oxidation. There are further additives that will improve the detergency and help the oil perform under extreme pressure.

Typically, engine oil is mostly hydrocarbons and its main feature is its viscosity which is the ability to form a lubricating film – it’s all about the resistance to flow of the oil. The oil must be viscous enough to maintain a film but not too viscous or it won’t be able to flow around the various engine components. Every oil has a viscosity index which is an indicator of how much the viscosity changes as the temperature changes. A high viscosity index shows that it does not change much as the temperature changes.

Gear oil

Gear oil is also primarily a lubricant but it has been designed specifically for transmissions and transfer cases. It must have a high viscosity and most of the time it will contain organosulfur compounds.

A specific set of additives makes sure that it can do the job that you need it to do. There will probably be an extreme pressure additive and an anti-wear additive which will help the oil to withstand the hypoid bevel gear sliding action. Typically, dithiocarbamate derivatives with sulfurized hydrocarbons are used.

Gearbox oils sold in the US will be awarded an American Petroleum Institute GL rating. The oils with higher GL-ratings can withstand more pressure. Most modern gearboxes require a GL-4 oil.

Air filter oil

Dirt bikes and other off-road motorcycles generally have oiled foam and fabric filter elements rather than the paper filters that are commonly found in cars. They are able to better hold dirt and keep the air flowing to the engine. The foam filters need to be oiled to work properly.

Filter oils are basic petroleum oils or synthetic oils. Some can even be vegetable-based oils which are biodegradable. Synthetic oils can withstand very high temperatures and are very good at saturating the filter evenly and completely. They are easier on your filter and the foam doesn’t degrade as quickly.

If you have no air filter oil available, it is possible to use regular motor oil as an emergency measure. However, this should not be done on a regular basis because it pools in the airbox and distributes in the filter unevenly. It can also be sucked through the intake tract. A specially designed air filter oil will have special additives to make sure that this does not happen.

Motor oil poring

Best Dirt Bike Oil FAQ:

Q: Is automotive oil bad for my dirtbike?

On the face of it, automotive oil (used in regular passenger cars) and dirtbike oils are very similar. However, before you rush in and use automotive oil in your dirtbike, you should know a couple of facts.  Firstly, many (but not all) dirtbikes have common sumps so the motor oil is used to lubricate and to cool the transmission. In regular cars, the transmission is lubricated by ATF fluid which has frictional properties that are needed for the way it works in the transmission. Regular engine oil cannot do this. Therefore, the engine oil that you use in a motorcycle, has to be able to lubricate the transmission and must have the same level of friction modification that a typical car oil does. It must also be able to prevent lock-up and slippage. For this reason, it will not contain the friction modifiers that automotive oil would have. Secondly, motorcycle engine oils are designed to break down viscosity quicker than automotive oils. They, therefore, give very good protection against viscosity loss.

Q: Should I separate the engine and transmission oil?

In most dirtbikes, the engine and transmission oil are the same thing and there is a common sump. Motorcycle-specific oil has different additives that allow it to do two jobs so there is no need to use separate oils.  Zinc and phosphorus are additives that make the oil more resilient and these are found in motorcycle oil but not in automotive oil. They have been cut out to reduce emissions from the exhaust gases in cars.

Q: How often should I change my oil?

Opinions on how often a dirt bike should have an oil change can vary a great deal. Most riders agree that it needs to be done after 10 hours of riding but others change it after just three hours of riding. Others think that every 10 hours is too frequent! There are some owners who look at the oil and if it has particles contaminating it, they change the oil. Always refer to the manufacturer’s manual to get a recommendation for your particular dirt bike.

Q: Can I learn something from my old oil?

It is always worth having a good look at the oil that you drain out of your bike. If you have to top up the oil all the time, it may be because the oil is getting into the combustion chamber. This may indicate that you have worn valve seals or worn piston rings that need to be replaced. If the oil is a creamy color, it generally means that it has water mixed with it so moisture is somehow getting into it. Most of the time, this means that you have a leaking water pump seal. Finally, look out for pieces of metal in the oil. Small pieces are quite common and are not a cause for great concern but larger pieces can mean that components are getting damaged. Some riders have found things like gear teeth in the oil because they have chipped off. Motocross in UK

Our Top Pick

Our top pick versatile mineral oil for all types of motorcycles as well as ATVs and side-by-side vehicles. It is a 4-stroke all-purpose oil that will give you stable clutch performance and protect from wear and tear.

It is a blend of top-quality mineral oil with ultra-clean additives and has anti-frictional properties and wet clutch performance.. You can be sure that it meets or exceeds the requirements laid down for this type of oil by JASO MA. This is a genuine OEM Yamaha Product.

Sources:

  1. The 2 Stroke Dirt Bike Engine – Dirt Bike Planet

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