2-Cycle Oil Mix Calculator & Chart

Outboard engines, leaf blowers, weed trimmers, and other equipment with small engines often have a 2-cycle, also known as 2-stroke, engine. If the engine has a single fill port for both engine oil and gas, it is a 2-cycle engine that requires a specific mix of oil and gas to function properly.

What Is the Right Ratio?

The mixture of gas and oil is written as a ratio that represents the parts of gasoline and the parts of oil. The ratio needed in the 2-cycle oil mix for your engine can be found in the equipment operator’s manual or on the engine label. If you cannot locate either, but know the equipment’s age, refer to the following: most handheld equipment manufactured before 2003 requires a 32:1 ratio; most handheld equipment made after 2002 uses a 40:1 or 50:1 ratio. Most outboard motors require a 50:1 ratio.

How to Create the Oil Mix

  • Pour the correct amount of 2-stroke oil into a clean gas can.
  • Add the correct amount of gasoline.
  • Stir or shake the container to mix the oil and gas.
  • Use the mixture within 30 days or add fuel stabilizer to extend the shelf life.

2-Stroke Oil Mix Calculator

  • For a 50:1 ratio of gas to oil, use 2.6 fluid ounces of oil per gallon of gas.
  • For a 40:1 mixture, use 3.2 fluid ounces of oil per gallon of gas.
  • For a 32:1 mixture, use 4 fluid ounces of oil per gallon of gas.

Important Warnings

  • Do not use automobile motor oil, which contains noncombustible additives that will damage your engine; only use 2-cycle engine oil.
  • Do not use gasoline with more than 10 percent ethanol, which attracts moisture, causes gasoline to break down, and can lead to engine damage.
  • Do not guess at the right ratio or approximate the amounts of either gasoline or oil; your engine requires a specific mixture of fuel and lubrication to run properly.
  • Do not combine the gas and oil in the engine directly; always mix them in a separate, clean container.
  • If your engine has been idle for more than a month, such as when coming out of winter storage, check the fuel to make sure the mixture hasn’t degraded.

The mixture of gas and oil is written as a ratio that represents the parts of gasoline and the parts of oil.

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  • There are some gas stations that sell ethanol free gas. Check out google or equivalent in your area to find them. This gas is much better but you may also need to add a little octane booster since many only sell 87 octane ethanol free gas.

  • “Check the fuel to make sure it hasn’t degraded” – how is this done?

    • There can be some visual indicators but we would recommend having it tested.

  • I’ve got a 1966 6hp Johnson boat motor what’s the mixture for gas

    • It depends on what your recommended ratio is. Theses are our recommendations though:
      For a 50:1 ratio of gas to oil, use 2.6 fluid ounces of oil per gallon of gas.
      For a 40:1 mixture, use 3.2 fluid ounces of oil per gallon of gas.
      For a 32:1 mixture, use 4 fluid ounces of oil per gallon of gas.

    • Outboards are 50:1

    • I am pretty sure it would be 20:1. Equipment builders in the 60s were less worried about 2-cycle emissions. A higher ratio would provide less lubrication that could damage the engine. Using 40:1 2-cycle oil you want to use 6.4 ounces or 2 of the premeasured 3.2 ounce bottles per gallon of gasoline. If you are in the process of rebuilding the engine you might want to have the valve seats hardened. The engines built back then relied on the lead in the fuel to protect the valve seats.

      • Valve seats in a 2-stroke outboard engine? Unlikely.

  • how many gallons of gas will 16oz of oil treat?

    • That’ll depend on your manufacturer’s recommended ratio. Please check the recommendation and then the chart should help you see the answer!

  • My 3 hp Johnson says 1/2 pint to one gal. Of gas. Is that 16:1?

    • Yeah that’s the correct ratio!

  • I have an early 70s chain saw with a recommended mixture ratio of 20:1. I have been told that the newer 50:1, 2 stroke oil can be used in older engines at the lower ratio of 50:1. What are your thoughts on this?

  • How much oi is 66:1 ratio?

  • Where is the 25:1 ratio

    • You’ll need to use aproximately 5.2 fluid oz of oil per gallon of gas.

      • I have a mini chopper! Not sure of the year? or recommend ratio! It is geared for power not speed which tells me the heavier load would require more oil. higher oil to gas ratio it will probably smoke a bit going up hill but I’m thinking better protection on the parts that
        On other motors are soaking in oil! But I don’t want to guess! I only weigh 160 to 166 and it scoots along pretty good! But I have been putting 1 of those little baby oil container in a metric gas can not sure how to adjust to metric? Would it be a little over a gal? And I am trying to under stand why the higher the first number is the less oil
        Is added??? So the newest motors are more efficient on gas? The first number is ounces of gas? And the second number oil? But then 50 to one dose not balance out right? 32 oz is a gal correct? So your chart says 3.2 oil for 50 to one so it kinda makes sense! But can’t we make it simple? Instead of sensible that ounce for ounce ratio!? Or is that what it is? I keep wondering how much life I am robing from
        My funnest mode of Transportation, every
        Time I have to refuel? And could I get a little more speed out of her if I cheat down the oil a smidge? It has flames on the tank and I got a Santa white fluffy beard and I wear a army issue helmet with a bullit dent in it! And act like I am gonna start some trouble I walk around all
        Puffed up with a scowl on my face ! Anyway can you splain it too me so that I know that it’s right! Use the 20/to one for reference I think
        That it used to say that on the cap!
        Kick ass
        Sargent Santa

  • Your calculator, as with 4 other gas:oil calculators I’ve sampled, is WRONG!

  • retract my comment. distinction between ratio and proportion eluded me

  • I use Sunoco 260 GTX 100 octane ethanol free and unleaded. It comes from the factory with a stabilizing additive in the fuel . Runs great in all my small engines.

  • What about 3%

  • How much 50.1 do I put in 2 gallons of gas

  • I hope this will help someone who’s not the best at math, and if they didn’t see this comment, they’re mix up a whole Gallon of 5.1 bc they didn’t know that instead of mixing 2.6 Oz’s of oil, cut it in half, witch equals 1.3 Oz’s of 2str

  • i have a 2019 50cc gas scooter and don’t know what to run for it its a 2 stroke


  • I’m trying to mix 40.1 with a 2.5 jug

    • Use 8 oz of oil. I suggest not mixing more of the proper 2 stroke oil than the manufacturer calls for. Oil burns hotter than gas too much oil and you can seize an engine, ask me how I know.