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Help needed with fluid ratio

  1. Jul 10, 2015 #1
    I want to mix oil and gas by the tank for my leaf blower. The mix is 40:1 My tank holds 16 oz.
    The manual says 3.2oz. of oil per 1 gal. of gas. I came up with 2.4 teaspoons of oil to the 16oz. tank. Am I right?. The reason for this question is that I don't use the leaf blower that often and mixing a whole gallon is too much. Thanks
  2. jcsd
  3. Jul 10, 2015 #2
    That is the right conversion, but might be the wrong answer. A lot will stick to the measuring spoon if you do it that way. Running two cycle lean can ruin an engine. Running with a bit too much oil just produces more smoke and reduces power. There is no risk to an engine running a 1:40 design at 1:32, and some margin for error could save you if too much oil sticks to your measuring spoon.
  4. Jul 10, 2015 #3


    User Avatar
    Homework Helper

    Yes, you're correct. Since you want 1/40 the amount of oil to the amount of gas you're using, then you want 16/40oz of oil, which equates to 2.4tsp.

    I didn't even realize teaspoons were a valid imperial unit of measure until now.
  5. Jul 10, 2015 #4


    Staff: Mentor

    Yes. 16 oz = 1/8 gal, so you want 0.4 fl. oz. of oil. According to this online conversion tool (http://www.thecalculatorsite.com/conversions/liquidvolume.php) 0.4 fl. oz = 2.365882365 teaspoons, which is pretty close to what you show.

    Instead of converting to teaspoons I would just put the oil in a measuring cup (such as a Pyrex measuring cup), and put in a little less than 1/2 oz.
  6. Jul 10, 2015 #5
    Thanks for the quick reply. Hope I wasn't to off the wall with this question.
  7. Jul 10, 2015 #6


    Staff: Mentor

    Nope. And keeping in mind what Dr. Courtney said about the oil sticking to the thing used to measure it, once you have the right amount in the measuring cup, you could fill the cup the rest of the way with gas, and put it into the leaf blower tank. Doing that a couple of times should get most or all of the oil.
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