If 2-Stroke Oil Is Used in a 4-Stroke Engine...

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Not a bit of harm. I use 2-stroke mix gas in everything. It may smoke a tiny bit more than regular gas. Remember, the 2-stroke oil is meant to be burned in a combustion chamber.
 
If you happen to have gas that is laden with 2T oil and you try to burn it in 4-stroke engine, it won't harm it esp. low tech lawnmower engine such as B&S, etc.

my 2c's worth.
 
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Not a bit of harm. I use 2-stroke mix gas in everything. It may smoke a tiny bit more than regular gas. Remember, the 2-stroke oil is meant to be burned in a combustion chamber.




Yes, I've heard/read about people using a 2-stroke's gas/oil mix as their fuel in a 4-stroke, and I know about the 2-stroke's oil being burned, but as the story that prompted this question was told to me, 2-stroke motor oil was used in the crankcase of a 4-stroke engine. The fuel was plain old pump gas.

Also, the engine was overfilled; from what I was told, the smoke was rather impressive and decimated the local mosquito population. The question is, how might the engine have been harmed, and is changing the oil and cleaning the plug about all one can do in that situation?

Sorry if my original question was vague.
 
First off 2-cycle oil has solvent in it to help it mix with gasoline. This in itself thins the oil. The 2-cycle does not have any of the additives in it that a 4-cycle engine needs. Depending on how long this engine was run, the best thing to do it get rid of the 2-cycle oil and fill it with the proper amount of recommended oil and see what happens. Unless the spark plug is fouled there is probably no need to do anything with it. Under the worse case the cylinder walls are scared and the bearings are worn badly.
 
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...what harm might have been done and what corrective measures need to be taken?




Your question is not specific enough and people are answering different questions.

Where, specifically, is the 2-stoke oil being used in the 4-stroke? In the crankcase as motor oil? Or are you referring to the use of 2-stroke premix as fuel for a 4-stroke.

These two questions have two very different answers.

If you're using two stroke oil as 4-stroke motor oil - get it out of there ASAP and do a short OCI to rinse all of it out.

If you're burning pre-mix in a 4-stroke, don't worry about it too much in small engine outdoor power equipment. Don't let the concentration get TOO high if you're talking about a catalytic converter equipped road vehicle.

Craig.
 
If the engine wasn't ran too long, it's probably OK.
Overfilled might have been a blessing in disguise, IF it didn't blow a seal.
I'd just refill with the proper oil and hope.
 
Chances are, if the engine didn't slowly sieze up you're fine. You may have shaved a year or two off the overall life of the mower, but these days, you can make a cheap one last for 10+ years or more.
 
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