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Additives for ethanol?

An old Mantis (two cycle mini tiller) would not run right. I took it for repair and was told the ethanol in the gas ruined parts in the carburetor. They rebuilt it and told me to use an additive going forward. There was also an article in the Lauren Fix column in my newspaper recommending a specific (and different) additive to prevent auto damage from the ethanol. Auto parts stores now have several different additives for this purpose. The questions. Is 10% ethanol bad for engines? Is it bad for all engines? Which, if any, of the available additives do any good?

Hopefully, the parts in the carb rebuild kit will be updated ones that can tolerate the ethanol…Vintage motorized equipment frequently used “pumper” type carburetors that contain several rubber diaphragms and check-valves that are attacked by alcohol, any type of alcohol…This problem has been resolved in newer equipment and in the repair kits for the older equipment.

I can not see how a fuel additive can protect susceptible rubber parts from being attacked by alcohol…

One defense is to drain the fuel and run the carburetor dry when the equipment will be stored for more than a few days…

If your lawn mower and other small gas motors (chain saw, etc.) are 5 or more years old they likely weren’t designed to handle ethanol in current gas. Most cars, 15 years old and younger, can handle the alcohol but older cars perhaps not. Boats and other marine engines are at a definite disadvantage and Marine additives to treat gas going into boats is very common.

The carb (4bbl Holley) on my ski boat ('87 w 351 ci PCM Ford block marine V8) had all kinds of a whitish, sand like, deposits likely from ethanol interacting with metals and plastics in the fuel system. Cleaned out the gunk and installed an new filter (hope it helps) and it made a huge difference in how the motor idles and runs.

These additives apparently do work, and should be used in “older motors” including lawn and garden equipment.

Unfortunately, running the carb dry is not only insufficient but the surfaces are already coated and it does less good then making sure you use the correct ethanol additives. The enemy is time…run the equipment regularly enough so that fresh gas must be added. The problem with running dry carbs is that many of the plastic and rubber parts are designed to be used with gasoline and dry out without it. Nothing beats regular use.

One definite way is to replace the last fuel used with “Trufuel” or the like which I do with the generator which must start when I need it but can still be left for over a year.

For the last several years I always add the old “red” Stabil to the gas cans used to refill my mower, chain saws, generator, etc. You never know how long the stuff will hang around so I just treat it when I buy it. When I run out of the red stuff I will do the same with new “blue” Stabil which is for use with ethanol fuels. Still have a bunch of red stuff, so for now the boat is the only thing getting the new blue Stabil.

I also use old gas in the cans in my car after about 6-8 months if it is still sitting around so keep from getting stale fuel. Then I refill the cans with fresh fuel. In the winter I have a backup generator so I buy about 10 gallons of fuel just in case we have an area wide power outage, which seems to be pretty common in my rural area. So far I’ve never had to redo a carb due to stale fuel and varnish in the carb.

I don’t know how much to trust this info, but I recently did some work on a lawnmower carb. I bought parts from one of my local small engine places - one of those places that’s been around forever & everyone trusts. The guy who sold me parts told me that none of the new small engine stuff is coming out able to handle ethanol and that nothing has changed. These parts were for a Honda mower so its possible he just meant these parts. But I was surprised as I was going by the assumption that all the new stuff can handle it now. He said to use one of the additives for ethanol fuels - didn’t matter which.

I’m willing to spend a few $ to try to be safe, but I wish I had a good definitive answer as to which of the additives I should use. My car dealer has one brand. My usual auto parts store has another. The guy who worked on the Mantis recommends another. The woman who has a weekly column in my newspaper recommends yet another and says it is the only one. Does anyone who reads this have a recommendation based on more than hearsay?

Some of the guys in our fire company, by the way, went to a convention and came back with some very expensive gas that is said to contain no ethanol. In this case it may be worth it, because we want the chain saws and generators always ready to go, but you never know how long they will sit unused.


you got several …ACTUAL ANSWERS, read again.

dagosa told you what he uses.
uncleturbo told you what he uses.
and cigroller told you the advice he got, which I agree with, the brand doesn.t much matter when it’s all essentially the same stuff.

Myself ?
I’m reading these and learning in case I might need the additive.
But I haven’t yet.
My mower and weedeater are electric. I don’t have a generator, boat, chainsaw, atv, skido, dirt bike, or go kart.
The only potential old gas I have to pre-treat is in my 79 that I put gas into about once every two years.
In that I use the red Staybil and have had no problems.

I have a carbureted motorcycle and the guy who had it before me had to have the carbs rebuilt after letting it sit over a winter with ethanol containing gas in the tank.

I use Seafoam gas additive to help prevent this problem and my bike has been trouble free for 3 years, 2 of which were bad winters where it sat unused for 4 months and started right up come spring.

I am sure other additives will work as well, but even with ethanol free gas, you should add a treatment / stabilizer if you are going to let the carb sit for an extended period of time.

Ethanol can attack the rubber parts of older carbs. An additive from the parts store is the way to go.

Newer small engines seem to be made using gaskets and O rings that are immune to the ethanol. I rebuilt the carb on my own 8- year old lawnmower last year and it showed no deterioration of the elastomers.