Bonehead mistake: 2 Cycle fuel in 4 Cycle tank

Discussion in 'Mechanic and Repair' started by kppurn, Jun 7, 2005.

  1. kppurn

    kppurn LawnSite Senior Member
    Messages: 426

    Yes, I'm an idiot. I wasn't thinking when I got back to the shop tonight and started filling the mowers for tomorrow. I started filling the Lazer when I realized I grabbed the two cycle can on accident. The five and half gallon tank is now full with about 1-1.5 gallons of two cycle and the rest straight.

    My question is, what the heck do I do now?
  2. dvmcmrhp52

    dvmcmrhp52 LawnSite Platinum Member
    from Pa.
    Messages: 4,205

    Just run it, it won't hurt running 2 cycle in a four cycle for a short period, it will only foul plugs and with the amount you're talking it won't even do that.
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    I agree with dvmcmrhp52 Wont hurt a thing !
  4. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,248

    One tank of this mixture will not hurt anything in my opinion. It would not hurt to add straight gas when you get the tank down a bit. Continued use will become a problem. I am aware of a lawn/landscape company that made a decision to run 2 cycle fuel in everything due to the screw ups of undocumented alien help. It happened to be leaf season and they brought in two large Billy Goat leaf vacuums with 18 hp Briggs Vanguards. They had used used 2 cycle fuel long enough to freeze the valves on both banks on both engines.
  5. fixer67

    fixer67 LawnSite Silver Member
    Messages: 2,098

    I agree. No damage done. Just run it out and when the tank gets down cut it with more straight gas. You may notice a little smoke until it is all gone. After it is gone check the plugs to see if they need changing but most likely they will be OK. I have seen engines that burn more oil than gas due to bad rings and only fouling plugs was a problem. Relax you have nothing to worry about
  6. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    You can run 2 cycle mix in your 4 cycle engines all the time if you want to. I have been in selling equipment for 20 years and have never allowed straight gas in my store. We usually buy about 100 to 125 gallons at a time and the mix oil is in the drums and containers before we go to the gas station. The only thing going out of our store or shop that doesn't have 50:1 in the tank is a diesel. This goes for all equipment we sell and service.

    This year I will sell around 1500 pieces of gas powered equipment, both 2 cycle and 4 cycle, and they will all have Amoco 89 (BP) octane mixed with Shindaiwa 50:1 oil. For about 12 years we used Opti 2 mixed at 100:1 in everything and the move to Shindaiwa 50:1 happened when we received a 55 gallon drum as a perk for large orders. My experience tells me that a high quality oil and a high quality fuel mixed according to the oil supplier's recommendations will work in just about any modern engine except for Tecumseh's 24 & 32:1 engines.

    Just growing older in Pensacola, Florida
  7. kppurn

    kppurn LawnSite Senior Member
    Messages: 426

    Thanks for all the replies. I ran it today with no problems. The plugs are fine as well.

    Thanks again
  8. CincyWolf

    CincyWolf LawnSite Member
    Messages: 78

    Like the others say, that small amount won't hurt anything. If you have 1.5 gallons of a premium 50:1 mix out of 5.5 gallons total you are not likely to know the difference.

    As a former dirt bike racer and tuner I will say that if you convert a straight gas engine to a pre-mix you need to pay attention to your carburetor jetting to make sure you don't lean out which could cause an overheating problem. On highly tuned 2 stroke engines even a small change in pre-mix strength will necessitate a change up or down in the main jet size - assuming if it was tuned just right before making the change. I found that most people didn't realize this and it made a difference between winning, losing and the ever dreaded DNF. I'm not saying that mower engines are the same as a high output motocross engine but the same principles apply.

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