I accidentally poured Briggs and Stratton SAE 30, 4 stroke engine oil into my 2-stroke snow-blower (note: in the right gas-oil proportion of 40-1). It starts and runs well; however, it seems to be giving out white smoke.


  1. Will it cause any permanent damage? If so, where is the damage (engine, spark-plug, gas-tank, carburetor)?
  2. Should I siphon the gas-oil mix right away, OR should I run the engine dry by running it continuously OR should I use my snow-blower as usual until the gas tank empties? I.e. what is the best corrective action?
  • 1
    Always the best advice is to operate it properly. So that would mean not operating it with the improper mixture, drain out all the tank and carburetor and finally refill with the proper mixture. Anything else is just not right even if no damage occurs.
    – Michael Karas
    Commented Feb 9, 2020 at 19:34
  • Thanks for your quick, well reasoned and firm suggestion. Appreciate it. Will execute right away - siphon out gas-oil mix and refill with proper-oil and gas mix.
    – user97485
    Commented Feb 9, 2020 at 19:38
  • 1
    Try to drain carburetor as well if it has any significant amount of fuel mixture in it.
    – Michael Karas
    Commented Feb 9, 2020 at 19:40

2 Answers 2


Unfortunately the most likely failure point for bad oil is the piston rings. This is a "get a new snowblower" tier problem.

Here's what I would do. Figure out how much fuel you mis-mixed (say 1 gallon). Get a jerry can at least triple that size.

Now, go make some new, additional premix fuel of twice that amount (e.g. 2 gallons) and mix the gas and oil correctly. So you could just use that directly and be good 2 go.

Now, drain the fuel out of the snow blower, and add it to this jerry can. Mix thoroughly.

Now, you have a can of 2-cycle gas that is 2/3 the correct oil and 1/3 not the right oil. The "wrong" oil still has a fair amount of lubricity, and the 2/3 will cover other needs. Go ahead and burn that, white smoke and all.

This won't damage your engine, and is also the simplest way to dispose of this mis-mixed fuel. You certainly shouldn't dump it on the ground, and mustn't dump it down a drain!

  • Thank you!!! Will follow verbatim. Appreciate your detailed process-steps!
    – user97485
    Commented Feb 9, 2020 at 19:55
  • Drained gas, replaced gas-(correct)oil mix and ran it again. No white smoke. Worked perfectly for 1/2 hour. Am all set!!! Thanks Harper and Michael Karas!!
    – user97485
    Commented Feb 9, 2020 at 22:10
  • 1
    @user97485, be sure to click the checkmark to toggle the question to answered.
    – fred_dot_u
    Commented Feb 9, 2020 at 23:18
  • Thanks. Have toggled the check-mark. Did not realize that it was there and hence never used it. Thanks for telling me about it.
    – user97485
    Commented Feb 10, 2020 at 2:44

Years ago, before they made "special oil" to use as the mixture for 2 cycle engines we used the recommended amount of regular motor oil. It could be SAE30 or SAE40 and did not matter. Today they sell "special oil" just for mixing with gasoline at many times the price of regular oil. The only difference in the old and new oils is the detergent in the new type oils. It is like that "special gasoline" that is pre-mixed and sold in quart cans for many times the normal cost. I do not see a problem but to be safe you could drain as the other guys have suggested.

  • Interesting!!! Actually I saw a YouTube video clip of a guy conducting experiments with SAE 30 oil mixed with gas and compared it with 2-stroke engine oil mixed with gas. The later mixed very easily while the former had to be shaken/stirred. However, he did not notice much difference after running it for an hour with 1) the running of the engine, 2) the spark plug nor 3) the inside of the engine. However, he did not recommend mixing SAE30 with gas and admitted to the fact that it was a small, limited time test.
    – user97485
    Commented Feb 11, 2020 at 2:01

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