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Crazy engine question

Discussion in 'Lawn Mowing' started by F6Hawk, Sep 13, 2004.

  1. F6Hawk

    F6Hawk LawnSite Member
    Messages: 195

    Ok, I know this sounds wacko, but bear with me a minute...

    Are you familiar with the Stihl 4-mix engines? If so, then why can we not simply run 2-cycle oil in our 4-cycle engines? Of course, the oil would have ot stay, but why can we not run the oil/gas mix instead of pure gas?
  2. 65hoss

    65hoss LawnSite Fanatic
    Messages: 6,360

    You can. I run a tank of Opti-2 mix thru my Lazer every so often to lube the top end real well.
  3. GreenMonster

    GreenMonster LawnSite Silver Member
    from NH
    Messages: 2,702

    I just ran amsoil mix in my compactor.

    It was all I had with me. :eek:

    I figured a little extra lube wouldn't hurt.
  4. Lbilawncare

    Lbilawncare LawnSite Bronze Member
    Messages: 1,117

    Every now and again is okay, but it is a waste to use mixed gas every fillup. The 4-mix engines are built to be run on mix gas.
  5. F6Hawk

    F6Hawk LawnSite Member
    Messages: 195

    Well, I thought about that... how can an engine be "built to run on mix gas", exactly? I mean, they use the gas & oil to lube the low end, as well as the cyleinder, but other than that, the only thing that is basically different is the exhaust valve(s), right? And the fact that a 4-cycle burns cleaner, because they "recycle" the unburned fuel (if so designed), or at least have e full stroke to burn the fuel off before exhausting it.

    Reason I wonder all of this, it would be nice to only have to have one can of gas in the garage, instead of two.

    Thanks for the replies!

  6. Precision

    Precision LawnSite Silver Member
    Messages: 2,995

    you will always need two cans. Unless you want to run your ZTR on mix gas. What a waste of money that would be. Not to mention that you would foul up your air filter quicker, and your plugs would be for hell after a few tanks and you would smoke like there was not tomorrow. Fill up a 21 inch and give her a go. It wasn't built for it, but it will run, but evertime I have seenit done they smoke like they just caught on fire.

    Besides you need that can of straight gas incase you forget to gas up the truck.
  7. dkeisala

    dkeisala LawnSite Senior Member
    Messages: 911

    This is pretty much exactly what a guy who builds two-stroke racing engines told me.
  8. Gravely_Man

    Gravely_Man LawnSite Silver Member
    Messages: 2,075

    As pointed out you can do this occiasionally but it can lead to fouled plugs and carbon build up if done too frequently. When I have some old gas/oil mix in the mower or the truck it goes.

  9. Tider6972

    Tider6972 LawnSite Senior Member
    from Alabama
    Messages: 649

    F6Hawk, as has been said, you can run 2 cyclye oil/mix in your 4 cycle engines. BUT...it only lubricates the top end, valves and upper cylinder.

    You MUST still put oil in the crankcase in order to lube the crankshaft, rods, and lower cylinder, or you'll have blown engines in VERY short order!

    You prolly know this, but I thought it should be stated!
  10. F6Hawk

    F6Hawk LawnSite Member
    Messages: 195

    Yes, I knew that part, in fact, I mentioned it above.

    With the new 4-mix engines, the gas/fuel mix lubricates the lower end prior to intake into the engine, if memory serves me correctly.

    As for the post about the clogged air filter & fouled plugs, can you elaborate on that one, please? How can it clog the air filter? I don't believe the oil/fule mix gets to the filter, does it? And as for fouled plugs, how come the plugs on the weed eater aren't fouled?

    Well, I didn't want to buck the system, just wanted to see what others' toughts were. Looks like I will be running 2 cans of gas forever, or at least until Exmark switches to 4-mix engines!

    Thanks for all the input...



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