Transmission Oils

All You Need to Know About Motorcycle Engine Oil, to Keep the Gears Turning

A motorcycle engine contains hundreds of moving parts and many of these components rub against each other when the engine is running.

Without oil, these fast-moving parts would eventually generate enough heat to expand and jam against each other, which happens when an engine seizes. A motorcycle engine's oil has several crucial jobs.

First of all, engine oil provides a protective barrier between surfaces and components so they can move freely. Second, as fast-moving metal parts generate heat, the oil keeps the engine at a safe working temperature.

Another important job of a motorcycle's oil is to absorb harmful particles. These particles are either a byproduct of the combustion process, such as carbon or grit or tiny metallic particles from the engine components.

Engine oil can only absorb so many harmful particles before it deteriorates, at which point it can't do its job. Allow the oil to become too dirty and broken down and it can lead to significant engine damage.

Choosing the Correct Motorcycle Engine Oil

Ensuring you have the correct oil in your motorcycle's engine is crucial. If in doubt, the first reference point should be the owner's manual. Its information will tell you the grade of oil and often recommend an oil brand.

The first part of the information is the most important, the grade of oil. The manufacturer may recommend a particular brand but check out MX blogs or talk to other riders to find which brand will work best for your motorcycle.

Types of Motorcycle Engine Oil

There are three types of engine oil and these are:

• Mineral

• Semi-Synthetic

• Fully Synthetic

Mineral oil is refined from crude oil and remains the go-to engine oil for over a century. This type of oil is a good all-round product for four-stroke engines and two-stroke specific oil.

Semi-Synthetic is an oil made of a specific blend of synthetic and mineral lubricants. Combining these oils provides the protective viscosity of mineral oil and the increased temperature flexibility of synthetic oil.

Fully Synthetic oil begins life as mineral oil before becoming so refined that its molecules alter. This altering at the molecular level gives the oil a more stable structure. The more stable structure of fully synthetic oil means it can handle more extreme conditions such as vast changes in temperature. This type of lubricant is also more resistant to breaking down from absorbing engine contaminates.

Oil Codes Explained

SAE10W-40This code is for the common engine oil used in many engine types. Here, we will use it as an example to help explain the meaning of the code.

SAE: Refers to the Society of Automotive Engineers. The Society's testing procedures on the viscosity or thickness of oil and how fast it flows determine the code's numbers.

10W: Here, the letter W stands for winter. Meanwhile, the number 10 refers to the oil's ability to flow at low temperatures, such as when the engine starts up. The lower the number, the faster the oil flow from cold.

40: This number defines the oil's ability to flow at higher temperatures when the engine is fully warmed up and operating normally.

Viscosity: As previously mentioned, an oil's viscosity is its ability to flow at low and high temperatures. The low-temperature viscosity, measured at 40°C, follows the letter W for winter. The second set of numbers shows the viscosity/flow rating for higher temperatures, measured at 100°C.

You may also see the initials API when looking at engine oil products. These letters refer to the American Petroleum Institute. Any letters appearing after API relate to the application's use. For example, SM for petrol engines or CF for diesel.

The same applies to JASO (Japanese Automotive Standards Organisation). JASO is the Japanese equivalent of API. Here, you may find the designation FD (two-stroke) or MA (four-stroke) following their initials.

Four-Stroke Engines

Four-stroke engines use mineral, semi or fully synthetic oil, kept in the sump or a separate tank. Both methods pump the oil under pressure around the engine. The owner's manual gives information on when to change the oil. However, most MX riders will complete an oil change every five hours of running time. At this time, they will also change the oil filter to maintain maximum performance.

Two-Stroke Engines

Two-stroke engines differ significantly from four-stroke engines when it comes to engine oil. Here, the carburetor delivers a gasoline and oil mixture into the crankcase. This action lubricates the piston, cylinder and crank bearings before being ignited. The clutch and transmission are sealed off from the crank to run in an oil bath of transmission oil.

Motorcycle oil is an engine’s life blood. If you want to ensure your bike runs stronger for longer, regular oil changes is the way to go.