The Advantages of Alkylate Fuels
Spring 2018

For years, STIHL, as an outdoor power equipment manufacturer, has been battling the ongoing challenges that come with using today’s gasoline in our handheld outdoor power equipment. Gasoline contains hundreds of additives that can have adverse effects on our equipment. One of those additives is Ethanol, which poses the largest problem in our equipment and we needed to find a solution. That solution is called MotoMix® and Moto4Plus. It’s an alkylate fuel which has been formulated by STIHL to run specifically in our machines. What’s special about it is that it doesn’t contain any of the harmful additives that gasoline does since we are able to pick and choose what goes into it. The benefits are a five year shelf life for new unopened containers, and two years once the container has been opened. This means that these fuels are good for two years in the entire fuel system, including the carburetor, with no negative effects.

Ethanol blended gasoline today starts a process called Phase Separation within thirty days of purchasing it and sixty days when using STIHL’s mix oil since it contains fuel stabilizer. The ethanol in the fuel is hygroscopic which means it is attracted to moisture and will bond at a molecular level. Phase Separation describes what happens to gasoline containing Ethanol when water is present. When gasoline containing even small amounts of Ethanol comes in contact with water, either liquid or in the form of humidity; the Ethanol will pick-up and absorb some or all of that water. When it reaches a saturation point, the Ethanol and water will Phase Separate, actually coming out of solution and forming two or three distinct layers in the tank.

Phase Separation can happen in underground or aboveground storage tanks, in equipment fuel tanks, and even in the gas can in your garage. When this happens, it can lead to serious and even catastrophic engine problems, without warning. When this Phase Separation occurs, there will be an upper layer of gasoline with a milky layer of Ethanol and water below it, and then in many cases, a third layer of just water at the bottom which is where the fuel pick-up is in our machines.

Ethanol is a strong, aggressive solvent and will cause problems with rubber hoses, o-rings, seals and gaskets. These problems worsen during extended storage when significant deterioration will take place. Hoses will delaminate, o-rings will soften and break down, and fuel system components made from certain types of polymers will either soften or become hard and brittle, eventually failing. Fuel system components made from brass, copper and aluminum will oxidize to the point of failure. Most of these materials can be found in our carburetors and fuel system.

When using MotoMix® and Moto4Plus, these issues are eliminated, therefore saving you time and money. It also burns cleaner which is beneficial to the operator, as well as, the environment.