TOTW: Don’t buy more octane than you need

The riding tips on these pages are my personal opinion about matters related to motorcycle riding. They are not the official position of any organization, and are for your consideration only. They are not hard and fast rules, they should not necessarily be applied in all circumstances, and they should not be applied without thinking. Always use your judgement and take all current safety factors into account while riding. You are responsible for your riding, not anyone else (especially me). These tips were originally published by a motorcycle riding course, called “Tip of the Week” (the reason for the TOTW in the titles).

What’s octane?

Octane is a gasoline rating that measures a specific combustion property of fuel. Strange as it sounds, octane makes gasoline harder to ignite. The higher the octane number, the more resistant the fuel is to pre-ignition, or knocking. Your engine needs a certain minimum octane rating, as specified by your manufacturer. Once you are using fuel with a high enough octane rating to resist knocking, using a fuel with an even higher rating accomplishes nothing more.

The problem is that because of popular use of the phrase “high octane” to mean “high power” or “extra strength,” there is a misconception that higher octane gasoline is higher quality, and that it will produce more power or better gas mileage. This is not the case. Octane doesn’t measure a fuel’s ability to produce power, just its anti-knock properties.

What about those flashy signs at the gas stations saying “super performance” on the high-octane pump? They’re not wrong, exactly, but it’s easy to confuse cause and effect. Engines designed for higher performance have a greater tendency to preignition, and often require higher octane fuel, so it’s absolutely true that if you have a high-powered engine you may need high octane. But the reverse is not true. Putting high octane gas into a low-performance engine does not make it more powerful.

Recommendation

You should use the octane grade your owner’s manual recommends. If you still get knocking (possible, for example, under different environmental conditions), try progressively higher octane ratings until the problem disappears. Once you have found a rating that works, however, don’t go any higher — you would be paying more for no benefit.

Some riders also advocate trying lower octane ratings than the manufacturer recommends. That’s a personal call, but my recommendation is to follow your manufacturer’s advice, to ensure your service representative is happy, warranty conditions are met, and so on.

“High Octane” may mean stronger coffee or louder music, but it does not mean more power in gas. Don’t pay for more than you need.


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