2 stroke mix in 4 stroke engines

Discussion in 'Mechanic and Repair' started by David Thompson, Apr 4, 2008.

  1. David Thompson

    David Thompson LawnSite Member
    Posts: 45

    One of the guys left me a Little wonder blower to work on today and as I prepared to drain the carb and tank the gas was blue ! So I got to looking around and found all 6 blowers 5 roto tillers 6 push mowers and 2 aereators
    all machines that have 4 stroke engines had 2 stroke mix in them.I started a few of them and they were running ok .
    Question ,,, Should I drain it all out and replace with regular unleaded ?
    or just let them run it out ?
  2. Tider6972

    Tider6972 LawnSite Senior Member
    from Alabama
    Posts: 649

    Use it; I often use mixed fuel in 4 strokes, it's good for them.
  3. Two Seasons

    Two Seasons LawnSite Senior Member
    Posts: 791

    If you use straight fuel, you'll be buying alot of new Stihl equipment!

    Stihl 4-mix engines do not have any crankcase oil, therefore, you need to mix 2-stroke oil with the fuel. Stihl recommends using the silver label 2-stroke oil---the HP ULTRA oil.
  4. David Thompson

    David Thompson LawnSite Member
    Posts: 45

    These were not stihl engines but honda and kawasaki . over head valve engines.
    The kind with big "regular unleaded " labels on the gas cap.
  5. jkason

    jkason LawnSite Senior Member
    Posts: 548

    Using 2-stroke mix in a 4-stroke won't hur it, but it will smoke.
  6. yungman

    yungman LawnSite Bronze Member
    from Calif.
    Posts: 1,274

    You put 2 cycle oil in gas for Honda, then you will make the Honda to have the same valve deposit issue as the hybrid 4 cycle engines like 4Mix and C4. Honda is so much more reliable than 4mix and C4 because it does not use oil in the gas so less to deposit onto the valves.
  7. KGR landscapeing

    KGR landscapeing LawnSite Bronze Member
    Posts: 1,544

    just let them use it up then fill them up real gas. 2cycle in a 4stroke wont hurt but if its the other way around its bad news
  8. Oldtimer

    Oldtimer LawnSite Bronze Member
    Posts: 1,458

    I have never allowed straight gas in my store. We use the same mixed fuel in every 2-stroke, 4-mix & 4-cycle engine that we sell or service. The only engines that we don't use mixed fuel in are running on diesel or LP.

    A lot of LCOs do not allow any container of straight gas on their trucks and trailers.

  9. yungman

    yungman LawnSite Bronze Member
    from Calif.
    Posts: 1,274

    You're kidding right, putting mix in 4 cycle lawn mower and Hondas.
  10. David Thompson

    David Thompson LawnSite Member
    Posts: 45

    I can kind of see the logic in it. The mistake in the opposite would cause catastrophic failure where as mixed gas in a 9 horse honda will just gum it up and foul the plug. At least I hope thats all it does.

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