What would happen if you ran oil/gas mix in mower?

Discussion in 'Mechanic and Repair' started by JDiepstra, Nov 3, 2009.

  1. JDiepstra

    JDiepstra LawnSite Bronze Member
    Messages: 1,510

    Long story short due to being in la la land today I ran my mower out of gas on my brothers lawn. I had enough regular gas in a can to get it back onto the trailer but not enough to finish the job. I thought about using the oil / gas mix can but didn't want to cause any issues. Can anyone tell me what would have happened if I used the mix in the mower in my sig? Thanks.
  2. M & MD Lawn

    M & MD Lawn LawnSite Senior Member
    Messages: 518

    I've often wondered the same thing, i figure it might not combust right or something since its not pure gas, idk
  3. starry night

    starry night LawnSite Gold Member
    Messages: 3,323

    I'm not sure what anyone else will say but I have run mix in a mower when I ran out of regular gas. I don't think the oil is enough to cause any problem, at least in the short run.
  4. greendave

    greendave LawnSite Member
    Messages: 219

    The rings will get WELL lubricated!

    If you run Amsoil 100:1 like I do, you'd probably never know the difference.

    Seriously, on a short term basis, you won't do any harm. If you ever do inadvertantly or out of dire need run mix in there, just make sure you fill the tank with your normal gas as full as possible, as soon as you can to dilute what mix you put in.
  5. tamadrummer

    tamadrummer LawnSite Bronze Member
    Messages: 1,102

    I run it every now and then. I will also run it in my truck every now and then. I run it in my small walk behind all the time. It is the only fuel that mower gets since I do not carry straight fuel in my mowers ever. Since I am running high quality fuel and oil and I don't believe that it will hurt the mowers at all.

    I don't know if it helps but it certainly isn't hurting it at all.
  6. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,249

    From what I have experienced I would suggest that it not be done for an extended period of time.

    When I was turning wrenches in a shop envoirnment, we once took in three Billy Goat wheel blowers with 11hp L head Briggs and a Billy Goat leaf loader with a 16 or 18 Briggs Vanguard OHV from a local lawn/landscape outfit. The complaint was that they would not start. A compression test on all of them revealed no compression. After teardown we found that all 4 units had exhaust valves stuck open and they were stuck open due to excessive carbon buildup on the stems.

    When I called the foreman of the company it was revealed that they were sending out only 2 cycle mix on the job because the south of the border laborers couldn't(or refused to) remember what units used regular gas and what used mix.

    I refuse to believe that it's a coincidence that all four units went down with the same symptom at about the same time.

    Your mileage may vary.


    STIHL GUY LawnSite Fanatic
    from CT
    Messages: 5,226

    i have run it in the truck before but not the mower
  8. M & MD Lawn

    M & MD Lawn LawnSite Senior Member
    Messages: 518

    why did u put in the truck?? was there a benefit?
  9. unkownfl

    unkownfl LawnSite Gold Member
    Messages: 3,837

    It won't hurt anything but the plugs. Yes more carbon would build up on the valves and ports but I steam(hot soak) my engines about every 100 hours anyways and about every 50k on vehicles when I change the oil and plugs
  10. lonestar245

    lonestar245 LawnSite Member
    Messages: 14

    IMO, if your doing this as a one time thing, there is really no harm to it, other than the extra load on the environment from burning oil. You know folks use "top end lube" in their cars- I used to run a gallon of diesel in my cars gas tank for the same reasons back in the 70's- a trick I learned from a Ford mechanic. Not sure I would go there with a modern fuel injection system though.

    I have even used "Marvel Mystery Oil" in a Briggs flathead that kept dying when it got hot due to what I suspected was a sticking valve. After dosing the tank with MMO, it never died again.

    I am also guessing with today's 50:1 synthetics (or better), that the carbon problem Dutch describes most likely would not happen in a 4 stroke, or if it did, it would take a lot longer to get to that point. But as Dutch points out- YMMV!

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