Managing Your Fuel

The Simplest and Least Expensive Solution:

• Buy plain E10 gasoline like is used in most automobiles. 87 octane is just as good as 93 for almost all four stroke lawnmower engines(A). If you are going to be mixing the fuel with two stroke oil as would typically be used in a blower, string trimmer or other hand held equipment then almost all of this type of equipment would call for 89 octane minimum but will run even better on 93 octane(A).

• At the time of purchase, treat it with Starton® while the fuel is fresh in your fuel can. One ounce of Startron® treats up to 6 gallons of gasoline. 

• When storing the fuel can, be sure to use the lids such that outside air is not circulating into the can. At the end of the season many people pour remaining fuel into a vehicle that uses gasoline and start over in the new season. 

• Do not use E85 or E15 (often labeled 88 octane).


Why Not Just Use Ethanol Free Pure Petroleum?

That works too and is a good solution if you have a convenient place to buy fresh pure petroleum. 

• Be careful to buy it at a station that sells a lot of pure petroleum. We have had mowers in our shop with recently purchased pure petroleum that would not run. We replace the fuel with our own fresh fuel and they do run. We believe some gas stations sell so little pure petroleum that it sometimes gets old before they sell it. 

• Remember, even petroleum gets old and leaves varnish. Fuel stabilizers existed before ethanol fuel for good reason. It would benefit you to still use one. STA-BIL® would be a good choice. Treat the fuel fresh when you buy it, not when you put it in the mower.

• 87 octane is just as good as 93 for almost all four stroke lawnmower engines(A). If you are going to be mixing the fuel with two stroke oil as would typically be used in a blower, string trimmer or other hand held equipment then almost all of this type of equipment would call for 89 octane minimum but will run even better on 93 octane(A).

• When storing the fuel can, be sure to use the lids such that outside air is not circulating into the can. At the end of the season many people pour remaining fuel into a vehicle that uses gasoline and start over in the new season.


Why Startron® as Opposed to Other Fuel Stabilizers for E10 Gasoline?

We recommend Starton® because we have been using it for over a decade and it has worked. That's not to say others don't work. Here is what we like about it:

• It is inexpensive: A bottle that treats 48 gallons of gasoline costs around $8. That's enough to last most people a year.

• Over treating is fine which means you don't have to take a lot of time precisely measuring. If you accidentally get twice as much as it calls for, no harm done. 


Do I Need to Run Stabilizer All Year Long or Just During Winter?

Mower & engine manufacturers suggest untreated fuel needs to be used within 30 days. The clock starts ticking when you buy the fuel, not when you pour it in the mower. That's a very short window. Fuel stabilizer is cheap, about 17 cents per gallon. That's a tiny fraction of the cost of a new carburetor. We use it all year long and recommend that you do the same. Startron claims to stabilize fuel for up to 2 years under ideal conditions.


History & Understanding the Problem:  

You don't have to understand the problem to solve the problem. Feel free to skip this section.

Gasoline getting old and causing problems is as old a problem as gasoline engines themselves. But it became more troublesome starting around 2007 for a couple of reasons. 

1 ) E10 Fuel (10% Ethanol / 90% Gasoline) became the standard fuel available at gas stations. 

• Ethanol is water based which is heavier than petroleum and after 30 days or so it starts to separate from the petroleum and fall to the bottom of the tank. Once separated it gets gooey / jelly like and eventually crystallizes. Combined with the amber hue of petroleum it often looks somewhat like brown sugar.

• Ethanol dry rots rubber & plastic parts. Some describe it by saying it "eats up" fuel lines or other plastic parts. This one issue has been resolved with ethanol resistant materials to the point that we see no more trouble today with fuel lines than we did before ethanol was prevalent. 

2 ) Manufacturers were redesigning nearly every small engine to accommodate Phase 3 EPA emissions standards for off-road small engines which required compliance by October of 2008. 

• These redesigned engines delivered fuel much more precisely. In the past one carburetor may have been used on many engines. Now nearly every engine had its own exclusive finely tuned carburetor. More precise fuel delivery meant finer pathways in carburetors that clogged more easily. 

• While most of the old carburetors would have withstood many layers of petroleum fuel varnish before giving problems, these new carburetors were not forgiving of old fuel and varnish even from pure petroleum. Add to it the even shorter term issues that came with ethanol and it created an epidemic of carburetor problems across the industry.


Bottom Line: 

Fuel left in your mower to get old can deteriorate and leave a residue. Pouring the old fuel out after the fact and replacing it with new fuel does not get rid of the residue. Fuel can also go bad sitting in your fuel storage can before being poured into the lawnmower. As this residue builds up in your engine's carburetor it first reduces performance making the mower run rough and harder to crank. Eventually it builds up to the point that the engine will start. A common symptom is for the mower to start and run for a few seconds and then stop running. There are some parts of the carburetor that are accessible to be cleaned but even if we can get it running with cleaning, it probably won't run like new. A new carburetor is usually the best solution and often the only solution. 


Will the Manufacturer Warranty Cover Problems Caused by Fuel Deterioration? 

This is not the manufacturer's responsibility to cover because it is not a defect and it is outside their control to prevent it from happening, but is easily prevented by the equipment owner. 


(A) Consult your engine owner's manual for appropriate octane fuel ratings and 2 cycle oil mix if applicable.