As I was waiting at the shop the other day to pick up my chainsaw, I heard strong words up ahead in line: something about the government and the EPA and ethanol. When my turn came at the counter, the saw doctor looked up from my bill, with its itemized list of new gaskets and filters, and said, “Same for you. Stop using gas that’s more than a month old.”
More than a month old? Didn’t it used to be more than a year old? What’s the deal?
Back in the proverbial good old days, when gas was leaded and two-cycle engines exhaled blue flames, experts recommended shaking up your gas can every now and then to keep the two-cycle oil well mixed. Keeping the same gas for years on end was frowned upon, but in my memory, at least, it was commonly done.
In the 1990s, when two-cycle engines became much cleaner, the “old gas” recommendations began to tighten up. I recall six months being the limit, or maybe “a few months.” The theory was not only to keep the two-cycle oil well mixed but also to keep the gasoline itself fresh, since gasoline (unlike crude oil) is a relatively volatile product that degrades over time. The newer, cleaner saws required higher gasoline quality to run properly. Some dealers started recommending buying the highest-octane fuel for sale at the pump, while others recommended 89 octane because the higher grade did too much cleansing.
The new development is ethanol, which is now routinely mixed with gasoline to help meet air emissions standards and reduce dependence on foreign crude. The ethanol can become separated from the gasoline and two-cycle oil over time, adding to the need to keep things well mixed. Ethanol is also a higher-performance fuel than gasoline, potentially requiring that saws be tuned differently, a vexing problem since ethanol blends at the pump vary with the season and region of the country. Finally, ethanol is hydrophilic, meaning that it tends to absorb moisture from the atmosphere over time, further degrading the quality of the fuel and gumming up the works.
While everyone seems to agree on the problem, few agree on the solution. My saw doctor recommended turning the saw upside down and draining out all the fuel between uses. My chipper-rental guy said to leave the fuel in there but add fuel stabilizer. A well-informed friend of mine pointed out that most fuel stabilizers are not designed to work with ethanol. A tour of the web revealed the usual contradictory information: the most elaborate advice, from Stihl USA, was to drain the fuel after every use, idle the carburetor dry, drizzle two cycle oil into the piston after removing the spark plug, and store the saw in a heated, low humidity environment. The simplest advice was to do nothing, on the theory that new saws are designed to run on ethanol blends.
While waiting for the smoke to clear, my approach is going to be this. Mix up only small amounts of fuel outside of firewood season, shake it up before each use, and dispose of older fuel by running it through the lawn mower. (The mower is a four-cycle engine that doesn’t have a catalytic converter: opinion varies on the effects of running two-cycle oil through a vehicle’s catalytic converter.) Pour old fuel out of the saw between uses (figuring out some way to do this without spilling gasoline all over the garage) but don’t run the carburetor dry since my saws are stored in the garage and moisture might creep in if the saw’s seals dry out. Meanwhile, use only two-cycle oil that’s been designed for use with ethanol blends and monitor progress on the fuel stabilizer front.
I do hope that someday there’s a decent chainsaw on the market that doesn’t run on gas. Or ethanol. Or whatever it now is.