Halderman:
You are correct that most gasoline today contains ethanol. While ethanol (ethyl alcohol) is used to increase the octane rating of the fuel, it does absorb moisture from the air. Here is what happens:
• Moisture in the air is absorbed by the alcohol in the fuel. This is why it is important to keep the fuel tank full when storing a mower to keep air out from the tank.
• When water is absorbed by the alcohol, it tends to separate from the gasoline. This is called “phase separation.”
• The alcohol-water mixture is heavier than the gasoline and sinks to the bottom of the tank.
• The engine draws the fuel from the bottom of the tank, which means that the engine is using this alcohol/water combination, leading to hard starting or no starting in the spring.
Most experts recommend using ethanol-free gasoline in vehicles that are being stored for any length of time to help reduce moisture from being absorbed. Visit www.pure-gas.org to find a station that sells alcohol-free gasoline. Some of the stations listed have a special pump that may not be labeled so be sure to ask at the station where the alcohol-free gas pump is located. It is usually more expensive and often 89 or higher octane, compared to 87 for regular unleaded gas.
Most experts state that the shelf life of gasoline is 90 days. Shelf life means that the gas works like new for 90 days, but after that the light ends start to evaporate and oxidation starts to occur that affects performance. I recommend a gas stabilizer be added to the gas container to allow the gas to remain fresh for six months or longer.
Always fill the tank with fresh gas and use fresh stabilizer. Also try to use Top Tier gasoline in all vehicles, not just in mowers. Top tier gasoline has engine-cleaning chemicals to help reduce engine deposits, more than specified by the Environmental Protection Agency.
For a list of brands that are top tier, visit www.toptiergas.com.
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