What is the best fuel type for lawn mowers and small engines?


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What is the best small engine or lawn mower gas?

Fuel for your lawn mower or outdoor power equipment must meet these requirements:

  • Clean and fresh - fuel can begin to deteriorate in as little as 30 days

  • A minimum of 87 octane/87 AKI (91 RON); If operating at high altitude, see below

  • Gasoline with up to 10% ethanol (gasohol) or up to 15% MTBE (methyl tertiary butyl ether), is acceptable. Some fuel stations are now selling gasoline with up to 15% ethanol. This E15 product is not recommended or approved for use in small engines.

  • A canned fuel product such as Briggs & Stratton® Advanced Formula Ethanol-Free Fuel can also be used. This fuel combines ethanol-free unleaded gasoline with a fuel stabilizer to prolong the life of the fuel.

  • Fuel RVP rating is equally as important as the octane rating. Gasoline refineries raise and lowers fuel RVP ratings seasonally to account for the differences in temperature.

  • Summer Fuel = low RVP rating

  • Winter Fuel = high RVP rating

  • ** This rating varies from state to state also **

Note: LOOK BEFORE YOU PUMP! Do not use unapproved gasolines, such as E15 and E85. Do not mix oil in gasoline or modify the engine to run on alternate fuels. Use of unapproved fuels will damage the engine components, which will not be covered under warranty.


Fuel Recommendation for High Altitude Climates

At altitudes over 5,000 feet (1524 meters), a minimum 85 octane / 85 AKI (89 RON) gasoline is acceptable. To remain emissions compliant, high altitude adjustment is required. Operation without this adjustment will cause decreased performance, increased fuel consumption, and increased emissions.


Mixing Oil & Fuel for Small Engines

  • 4 Stroke Cycle Spark Ignited Engines: Do not mix oil in gasoline, or modify engine to run on alternate fuels. This will damage the engine components and void the engine warranty

  • 2 Stroke Cycle Spark Ignited Engines: Always mix a high quality, 2-cycle oil, such as Briggs & Stratton lawn mower oil, at a 50:1 gas to oil ratio

Don’t know what type of engine you have? Consults your Briggs & Stratton manual


Small Engine Fuel Storage Tips

The use of a fuel stabilizer is imperative to a fuel system that does not get used on a daily basis. Issues that are presented because of fuel degradation, are issues that are not covered under the warranty guidelines for the engine. Briggs & Stratton offers an Advanced fuel treatment & stabilizer formula, and recommends that it be used at every fill-up.

With fuel treatment, you don’t need to drain costly gasoline from your small engine to safely store your equipment. Simply follow these steps for proper storage:

  • Add fuel treatment according to instructions
  • Run engine for 2 minutes to circulate stabilizer through the fuel system
  • Store lawn mower or equipment in clean, dry place for up to 24 months

If gasoline in the small engine has not been treated with a fuel stabilizer, it must be drained into an approved container. Run the engine until it stops from lack of fuel.

The use of a fuel stabilizer in the storage container is recommended to maintain freshness. It is also recommended that fuel is purchased in quantities that can be used within 30 days. This will assure fuel freshness and volatility tailored to the season.

For additional information on fuel type, please contact Briggs & Stratton engine experts near you!

WARNING: Fuel and its vapors are extremely flammable and explosive. Always handle fuel with extreme care. 


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