Why Choosing the Right Octane Matters for your ATV
Gasoline is an essential part of your ATV or side-by-side and choosing the correct type will help your unit run properly for a long time. The short answer to the question of what fuel to use– dump in whatever fuel the manufacturer recommends. But, one of the keys to ATV ownership ATV ownership is understanding why your vehicle requires a specific octane rating, and how that choice affects performance. Let’s go over what to look for and consider before filling up the tank.
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Start with the Manufacturer’s Recommendation
This information can be found in your owner’s manual and will change from model to model, so be sure to check the manual that came with your particular unit. Generally, most brands recommend 87 octane gasoline, though you’ll also find recommendations for 91 octane, usually on high performance models.
Regardless of commonality among brands, it’s safer to ensure you check the owner’s manual to avoid the risks of a mismatched fuel. For instance, adding low octane fuel to a high compression engine could lead to that fuel igniting before it’s supposed to, leading to engine knocking, power loss, worse fuel economy, and possibly damage.
Running higher octane fuel in an engine with a lower octane rating has less likelihood for damage, it doesn’t provide any real benefit in engines not designed for it.
Understanding Octane Ratings
Let’s first break down what the octane rating itself represents. Octane measures how much compression a fuel can withstand prior to igniting. The higher the octane rating, the less likely it is to pre-ignite under pressure, which is why performance machines are designed for higher octane fuel, as they typically run at higher compression.
There are two different commonly used methods to measure the octane rating, resulting in the RON and another value known as the Motor Octane Number (MON).
RON vs. MON vs. AKI
In most of the world you’ll only find the RON value listed for fuel, but in North America it is standard practice to combine the average of the RON and MON which results in the ratings we see at the pump, referred to as the Anti Knock Index or (R+M)/2. That abbreviation will be listed on the pump to let you know how the octane number was derived.
So when Yamaha says 86 octane or a RON of 91, they are two different values that describe the same fuel. If you just happen to be in a place that only uses RON values, you now know that it has to be 91, though most places in North America will use the (R+M)/2 value, which is 86.
Popular Make/Model Guidelines
Polaris
“Most Polaris Off-Road vehicles require unleaded gasoline with a minimum pump octane number of 87. Do not use fuel with an ethanol content greater than 10 percent. Octane in excess of 87 will not damage the engine but typically will not result in performance gains,” according to the brand.
Higher octane doesn’t automatically mean more power, despite common misconceptions, though Polaris outlines some specific models that do require 91 octane, like the RZR Turbo and Pro XP models. They require unleaded fuel with an octane number of 91. The brand advises against using fuel with a rating lower than 91 or fuel with an ethanol content greater than 10 percent.
Can-Am
Can-Am differs from Polaris, saying on its website you should simply use “unleaded gasoline, 91 octane.” When you look deeper into some owner’s manuals, though, you get a more detailed answer. The manual states that the Can-Am Defender needs regular unleaded gasoline with an AKI (R+M)/2 octane rating of 87, or an RON octane rating of 91.
Yamaha’s
For Yamaha engines, things are similar, though they include a new term we must learn. “Your Yamaha engine has been designed to use regular unleaded gasoline with a pump octane number of 86 or higher, or a research octane number (RON) of 91 or higher,” reads the owner’s manual from the Wolverine X2.
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Fuel Differences by Season and Location
Outside of just octane, there are some considerations you have to account for with the fuel you choose. First, there will be different fuel at the pump in the summer and the winter if you live in a place where it gets below freezing regularly. The winter fuel blend allows the gas to evaporate easier to get started in the cold, while the summer gas will have a harder time evaporating so it stays liquid even in hot temperatures.
Another pump octane you could encounter is 85, though this will only be in places with high elevation. As the oxygen is thinner, running a fuel with a lower octane rating makes it easier to combust, leading to an 85 octane fuel acting like an 87 when you’re at over 5000 feet.
Choosing the correct fuel for your ATV demands careful thought. However, by researching the previously mentioned factors, you can determine the right direction. Always keep general fuel guidelines in mind and consult your owner’s manual.
Stephen Elmer
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