2 cycle oil/gas mixture in a 4 cycle engine

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orangecrushcj7

Feeling the Heat
Hearth Supporter
Jun 30, 2008
352
Barre MA
So my wife decided to help out an pick up the leaves with our bagging lawn mower over the weekend while I was at work. I came home and she proudly asked, "Did you notice the lawn?" I was pleased to see there were no leaves. The next day I went out to the shed, and saw the little gas can I have that is labeled "16:1 Saw" that I use for the chainsaw, was out of it's place from the shelf, on the floor near the empty regular gas can. Long story short, she topped off the mower with the 16:1 chainsaw fuel. She claims it ran fine with it. I have yet to start it myself, for fear it may harm the engine. Do I need to siphon it out, or is it ok to run it the way it is? If I had to guess, it would just burn the oil that is in with the gas, and smoke like a 2 cycle engine, but I wanted to make sure it was ok to do so.
 
Orange Crush CJ-7 said:
So my wife decided to help out an pick up the leaves with our bagging lawn mower over the weekend while I was at work. I came home and she proudly asked, "Did you notice the lawn?" I was pleased to see there were no leaves. The next day I went out to the shed, and saw the little gas can I have that is labeled "16:1 Saw" that I use for the chainsaw, was out of it's place from the shelf, on the floor near the empty regular gas can. Long story short, she topped off the mower with the 16:1 chainsaw fuel. She claims it ran fine with it. I have yet to start it myself, for fear it may harm the engine. Do I need to siphon it out, or is it ok to run it the way it is? If I had to guess, it would just burn the oil that is in with the gas, and smoke like a 2 cycle engine, but I wanted to make sure it was ok to do so.
My mix is 50 to 1 and have use it in splitter before,may gum up the carb.shouldnt hurt anything major
 
In my dirtbike days this used to happen a lot. Sometimes the lawnmower would get filled from the wrong can, etc...The worst that will happen is that it will foul the spark plug so badly that the engine quits won't run until you take the plug out and clean it. If it does stay running it will smoke like a SOB though.
 
Shouldn't hurt anything. As mentioned, it will smoke. If the tank isn't full, fill it to dilute the mix. Everytime you use the mower, I would top it off again to keep diluting the mix.
 
did it all the time,at the end of the season when we had lawn boy we'd dump the rest of the mix into the car.
 
My old man used to do the same thing every Fall. A little anti-freeze in there too? No worries. That Ranch King will burn anything....
 
Lucky!

Much worse the other way around...: putting lawnmower gas (straight) in the chain saw!
 
Frostbit said:
Lucky!

Much worse the other way around...: putting lawnmower gas (straight) in the chain saw!

Ouch, that hurts!

Chris
 
Hey, keep that gas and oil 2 stroke mix handy for some winter chain saw work!

You always need it when you don't have it.
 
There was a Car Talk call on this a while ago. A guy ran out of gas and only had mixed gas with him for his trimmer. I guess it smoked a lot.
I believe their consensus was that it really wouldn't hurt anything, other then perhaps fouling the plugs.

I sometimes run old chainsaw and trimmer gas in the old riding mower when its no longer good enough for the saw. I haven't noticed any problems and did this
a few times over the previous summer.
 
It will not hurt a thing.

This past week I was out of regular gas and put mixed in my lawn vacuum (like a lawn mower shape but just bags and shreds leaves into big bag behind it, brigs engine) to pick up leaves. It did not even smoke. Unless you run a heavy mix I doubt you will even see any smoke for that matter. You can always top it off with fresh gas if it makes you feel better.
 
I've never heard of any problems running old 2-stroke mix in a 4 stroke mower / lawn-tractor / splitter / etc. type engine. The old Briggs and Tecumseh engines in particular are not at all fussy, if you can get it through the carb they'll run on it - with more or less smoke than usual.

The newer Honda, etc. engines may be a bit fussier, but still shouldn't have any problems.

I know of people that put mix in their cars, but I've heard some commentary that there is a possibility that some of the compounds in modern mix oil might not be good for the catalytic converter - My guess is that a little bit probably wouldn't be that bad, but I wouldn't want to run a lot through a car system.

In either case, as other posters have suggested, it wouldn't hurt a bit to add more regular gas to dilute things a bit.

Gooserider
 
Won't hurt anyhting but your lungs...the worst thing that I could see happneing is you might foul your plugs if you use it too much.
 
Hopefully true, but the folks that were saying don't essentially claim that some of the additives in modern mix oil (designed to make it wear better so you don't need to use as rich a mix, and so forth) are made with metals that can poison your car's cat...

I don't know if it's true or not, but given the cost / hassle of changing a cat, I'd just as soon get rid of my surplus mix in an engine that doesn't have one...

Gooserider
 
My old gas goes in the lawnmower or my truck. It'll smoke a bit but that doesn't worry me. All you are doing is adding a little upper cyl. lubrication.

Matt
 
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