Keeping up with the scheduled oil changes is essential for your ATV’s proper performance and longevity. But how do you know what type, grade, and brand of oil to use, and what can happen to your machine if you use the wrong one?

As a general rule, you should use the type and grade of oil in your ATV as specified by the manufacturer in the owner’s manual.

In newer ATVs, it is always recommended to use the specified oil, as using a non-recommended type may void the warranty.

Continue reading to learn more about:

The differences between the three types of ATV oil.
Different grades (viscosity) of oil and why it matters.
What is the difference between two-stroke and four-stroke oil?
What factors should you consider when choosing what oil to use in your ATV?
Potential consequences of using the wrong type or mixing types and brands of oil.

How Do the Different Types of ATV Oil Compare?

ATV oils are classified into three primary categories, each defined by its basic chemical composition. These types offer distinct properties that are important to consider.

Mineral-Based Oils

Mineral oil has been around for the longest (more than 100 years) and is often referred to as conventional or regular oil.

Organic: Mineral oils are based on naturally occurring organic crude oil extracted from the ground and refined into various petroleum products, including mineral oil.
Least expensive: Mineral-based oils are a cost-effective option because they are made from readily available raw materials and undergo a simple manufacturing process.
Moderate lubricating properties and performance. Mineral oils offer good lubrication under most normal operating conditions.
Low viscosity index. Mineral oil is more prone to becoming thin or more liquid at high temperatures and thick and less liquid at low temperatures. When the oil becomes thinner, so does the lubricating oil film, reducing the oil’s lubricating properties. Wax in the oil makes it too thick to lubricate properly at extremely low temperatures.
Short re-lubrication period: Mineral oils, particularly when hot, don’t stick as well and need a higher continuous flow of oil to maintain lubrication.
Lower Oxidation Stability: Oil oxidation is a chemical reaction where the oil reacts with oxygen, forming hardened oil deposits known as sludge and increasing oil viscosity.

The oxidation process, often described as the oil breaking down, can speed up when exposed to catalysts like high temperatures, water, and acids.

Mineral oils oxidize much more quickly and are more affected by catalysts such as high operating temperatures. As a result, the service life of mineral oil is about half that of synthetic oils.

Lower shear stability: Oil shear is a change in viscosity caused by mechanical stress or shear, making the oil thinner. Mineral oil has a lower shear resistance than Synthetic oil.

Synthetic Oils

Artificial: Synthetic oils are made from chemically modified, highly refined, and purified mineral base oils or other non-organic raw materials.
Most expensive: The manufacturing process to make synthetic oils is much more sophisticated and, thereby, more expensive.
Excellent lubricating properties and performance: The superior lubricating properties of synthetic oils ensure less friction between mechanical components.
High viscosity index: Synthetic oils offer more minor variations in viscosity at high or low temperatures. In other words, the oil doesn’t get as thick when cold or as thin when hot and maintains its lubricating properties almost regardless of temperature.
Lower pour point: The pour point is the temperature at which the oils no longer flow and is considered a solid.
Good oxidation stability: Synthetic oil is not as prone to breaking down from oxidization when exposed to high temperatures. This is why synthetic oils last about twice as long as mineral oils.
Long re-lubrication period: Synthetic oil keeps the mechanical components lubricated for longer, thereby not as dependent on a high oil flow to maintain lubrication.
Excellent shear stability: Synthetic oils can better withstand high stress without thinning.

Semi-Synthetic Oils

Semi-synthetic oils are a blend of conventional mineral oils and synthetic oils. This type of oil offers a middle ground in price and performance between conventional and fully synthetic oils.

How and Why ATV Oils Are Graded by Viscosity

Like car oils, ATV oils are graded by oil viscosity on a scale developed by SAE, which is short for the Society of Automotive Engineers.

Viscosity is a measurement of a liquid’s resistance to flow. In other words, the viscosity number tells you how thick or thin the oil is. Oil with a smaller number flows easier than oil with a bigger number.

For instance, the type of engine oil required for my Polaris Sportsman is labeled as SAE 5W-50.

The first number relates to how the oil flows when it is cold. This is indicated by the letter W, which stands for Winter.

The cold rating is relevant to how the oil flows and lubricates the engine at startup in cold weather conditions before it reaches operating temperature.

Because oil becomes thicker when it gets cold, using a thinner oil with a lower cold rating is helpful to ensure good lubrication at startup in icy weather conditions.

The second number relates to how the oil flows at a normal operating temperature and how well it holds against thinning in hot riding conditions.

As the oil heats up, it becomes thinner, which can reduce its lubricating properties. Thicker oils with a higher hot rating typically maintain their film strength better and protect the engine internals better at high-temperature operating conditions.

Here are a few examples of the practical differences between different oil grades.

5W-50 oil flows more easily when cold than 10W-50.
5W-40 oil flows more easily at normal operating temperature than 5W-50.
5W-50 oil has a larger temperature operating span (bigger viscosity range) than 10W-40.

Low-viscosity oil is typically used in high-speed and low-load riding applications, while high-viscosity oil is commonly used in slow-speed and high-load applications.

How to Know What Type of Oil to Use in Your ATV

Now that you know more about the different variations of ATV oils, here is how to decide what oil to use in your vehicle.

What Are the Manufacturer’s Recommendations?

For most ATV owners, unless you ride in extreme riding conditions, your best bet will be to use the oil type and grade as specified by the ATV manufacturer.

In the owner’s manual, you’ll find information about

What type of oil to use.
Whether to use four-stroke or two-stroke oil.
What rating oil to use.
Minimum API service classification.

Fully Synthetic vs. Semi Synthetic vs. Mineral Oil

For most modern ATVs, it is recommended to use semi–synthetic oil (sometimes referred to as blend oil) or fully synthetic oil.

These are the main benefits of using synthetic oil over regular mineral oil in your ATV:

Improved engine health and longer ATV lifespan: Due to improved cooling, extended re-lubrication period, and superior thermal and high-stress properties, synthetic oils reduce wear on mechanical components, which results in a longer component lifespan.

More time spent riding: Better thermal stability and reduced oil breakdown from oxidization extend the service life of synthetic oils. This results in longer service intervals, less time spent servicing your vehicle, and more time available for using it.

Reduced overall cost: The only benefit mineral oil has over the other oil types is a lower purchase cost. However, because synthetic oils last about twice as long and when you account for reduced service costs, the initial cost-benefit quickly diminishes.

Better performance: The higher viscosity index of synthetic oil makes it more suitable for extreme temperature use, and improved lubricating properties help increase engine performance and reduce fuel consumption.

All in all, there are no good reasons for choosing mineral oil in a modern ATV. For most riders, the benefits outweigh the higher purchase cost of synthetic oil.

The only exception is if you are running a vintage ATV designed to be run with mineral oils. Some old engines need to run on mineral oil to avoid oil leaks.

Some manufacturers, like Can-Am, sometimes operate with one recommended oil type for hot weather use and another for all-season operation.

People given this option and ride their ATVs exclusively in the summer can save money by choosing the cheaper blend oil over the more expensive synthetic all-season alternative.

Engine Type (2-Stroke or 4-Stroke)

When shopping for ATV engine oil, you must be aware that there’s a difference between two-stroke and four-stroke oil.

In a two-stroke ATV engine, the oil is mixed with the gasoline to lubricate the engine’s moving parts and help keep it cool.

As the oil burns off with the fuel, it must be designed to burn as cleanly as possible without leaving harmful deposits inside the engine.

In a four-stroke engine, the engine oil circulates independently throughout the engine without interfering with the ignition process.

Overall, the formulas for two-stroke oil (2T) differ from four-stroke oil (4T), and you must ensure you use the right type as specified by the manufacturer.

Recommended Oil Viscosity Grade

The ATV manufacturer’s engineers recommend what oil grade to use based on factors like engine design, vehicle type, and typical operating conditions.

For most riding conditions, you should stick with the recommended viscosity grade, regardless of your chosen oil type.

This applies to all oils, including engine, gear case, and differential oils.

Nevertheless, you might need to consider using a different oil grade in extremely hot or cold weather conditions.

As the owner’s manual dictates, you must follow the ambient temperature operation range recommended by the manufacturer of the specified oil.

In my case, that won’t be an issue with a recommended operating from -40ºC to + 40ºC.

If your recommended oil has a smaller operating range or you plan on taking your ATV to the desert or on a polar expedition, please refer to your dealer for recommendations on a custom viscosity grade recommendation.

Ensure the Oil Meets the Minimum API Service Classification

Some, but not all, ATV manufacturers write something along the lines of this in the owners manual:

“If the recommended X-brand oil is unavailable, use a 4-stroke SAE5W-50 engine oil that meets or exceeds the requirements for API service classification SG, SH, or SJ.”

API stands for American Petroleum Institute, and the API classification indicates the oil’s performance properties. The API classification is typically located on the bottle or spec sheet.

If the manufacturer allows using a different oil brand, ensure the oil you select meets the minimum requirements.

Also, ensure you choose a wet-clutch compatible oil if your ATV has a common sump for the engine, clutch, and transmission.

Why It Is Best to Stick With the OEM Brand Oil

Most major ATV brands offer OEM oils, and you are widely recommended to use them.

ATV manufacturers spend a lot of time and money on their OEM brand oils to reduce the chance of oil-related failures. Before the oil gets a thumbs up from the engineers, it must undergo extensive testing to ensure it meets all requirements for a particular engine.

Aftermarket oil brands are not stuck with the burden of ATV warranties and, thereby, don’t have the incentive to spend anywhere near the same effort to tailor their oils to specific brands and models of ATVs.

Some have used non-OEM brands for years without any issues, but for most people, choosing OEM is the safest and best alternative, even if it might be a bit more expensive.

The Consequences of Using the Wrong Oil in an ATV

Potential consequences from using the wrong type or grade oil in your ATV include

Severe engine damage due to inadequate lubrication.
Reduced ATV lifespan from increased wear.
Poor performance due to not meeting engine viscosity and performance requirements.
Deposits buildup, which can clog passages and reduce oil flow.
Voiding the warranty.

Extensive engine wear or damage is typically not something you would experience after just one oil change using the wrong type of oil.

There’s usually no need to worry if you accidentally use mineral oil instead of synthetic oil as long as it meets the minimum API requirements and recommended viscosity grade.

However, if you consequently use the wrong type, you might be under-lubricating the engine, increasing wear and negatively impacting performance.

Also, the marginal cost saving from using a non-recommended oil is not worth the risk of voiding the vehicle’s warranty.

Warranty limitations regarding what oil you use can vary from manufacturer to manufacturer, so you must refer to the owner’s manual to know what is allowed.

To avoid these issues, it is always best to use the oil recommended by the ATV manufacturer and follow the recommended oil change intervals.

Is It Okay to Mix Different Brands or Types of Oil?

Generally, mixing oil brands and types is not recommended as it can lead to significant engine damage.

This isn’t primarily because the oil types are inherently incompatible but because various manufacturers may use different additives in their formulations, which might not blend or perform well together.

Choosing the Right ATV Oil: What You Need to Know