For most lawn mowers, regular unleaded gasoline with an octane rating of 87 is recommended. This is the standard octane rating in the U.S. and is suitable for small engines like those found in lawn mowers. However, there are a few additional factors you should consider to ensure you’re using the right fuel for your specific mower.
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Choosing the Right Gas for Your Lawn Mower
1. Octane Rating
The octane rating refers to the fuel’s ability to resist “knocking” or pre-ignition in the engine. For lawn mowers, which typically have small engines, using 87-octane gasoline is generally sufficient. Higher octane fuels (such as 89 or 91) aren’t necessary unless specifically required by your mower’s manufacturer.
2. Ethanol Content
Most gasoline sold at pumps contains up to 10% ethanol (E10). Ethanol can attract moisture and cause corrosion in small engines if stored for long periods, so it’s best to avoid fuels with high ethanol content.
- Avoid E15 or higher ethanol blends: Fuels with ethanol content over 10% (like E15 or E85) can damage small engines, including those in lawn mowers. Always check the fuel label before filling up.
- If you want to avoid ethanol altogether, look for ethanol-free gas (also labeled as “REC-90” or “recreational fuel”), which is sometimes available at gas stations or in small engine fuel options.
3. Fresh Fuel
Always use fresh gasoline. Gasoline starts to degrade after about 30 days, especially if it contains ethanol. If the gas is left unused for too long, it can cause issues like varnish build-up in the carburetor, resulting in poor engine performance or hard starting.
- Use a fuel stabilizer if you plan to store gas in the mower’s tank for an extended period. This will help preserve the fuel’s quality and prevent engine problems.
Tips for Fueling Your Lawn Mower
- Check your owner’s manual: Always consult the mower’s manual to confirm the recommended fuel octane and ethanol limits.
- Fuel stabilizer: If you are storing fuel for long periods (over 30 days), use a fuel stabilizer to keep the gas fresh and protect the engine from damage.
- Avoid premium fuel: Higher octane fuel (like 91 or 93) isn’t necessary for most lawn mowers, and using it won’t improve performance. Stick with 87-octane unless otherwise stated by the manufacturer.
Conclusion
For your lawn mower, use 87-octane gasoline with no more than 10% ethanol (E10). Avoid higher ethanol blends like E15 or E85, and always try to use fresh gas or add a fuel stabilizer if needed. Following these guidelines will keep your mower running efficiently and extend the life of its engine.
