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How to Mix Gas and Oil for Your Weed Eater

Weed Eater Oil Gas Mixture
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It’s not like filling up your car with gasoline.

Understanding oil:gas mixtures are one of the most difficult tasks for new weed eater owners. But it’s not just new owners – after a season or two away, it’s easy to forget the right steps to mix before refueling. How much oil is enough? No one wants to run their engine on the wrong fuel – even if it is a relatively inexpensive 2-cycle motor.

Using the wrong fuel can lead to serious issues.  You can end up permanently damaging the engine if you forget to put oil in the mix.  Even if you don’t damage your string trimmer, you will likely see either excessive smoke or reduced power if you don’t get the weed eater oil to gas ratio correct.

Not only will the right kind of fuel make your weed wacker operate efficiently, but it keeps it safe as well. Read on for more information to make it an easy exercise.

How to Mix two-Cycle Oil and Fuel Properly

Step 1: Start by reading the manual for your weed eater. You can get additional information regarding the fuel mixtures and fuel grade if you RTFM.  If you’ve lost or destroyed it, contact your manufacturer to receive another copy of it.  Often companies will have electronic copies on their website. 

MAKE SURE YOU NEED TO MIX YOUR OIL AND GASOLINE!  Some engines have an oil tank and self-mix.  You can damage your engine if you burn oil-mixed fuel in these tools.

Step 2: Use a safe container for the job.  I know you aren’t the person that mixes gasoline and a used milk carton, but just in case – DON’T!  It’s easiest if your gas gan has a long spout and a solid cap to keep the fumes in.  This is especially important if you are storing the remaining fuel in the garage.

Plastic cans have come a long way and are lighter than their metal counterparts.  I prefer them.

Step 3: Consider purchasing premium unleaded gasoline.  Going with the cheap stuff can prove to be a big problem later on.  In reformulated gas areas, you’ll sometimes find ethanol-free gas at the higher tiers. This is a lifesaver for older gas equipment.

Step 4:  Make sure you use a high-quality oil.  STIHL premium quality two-cycle engine oil is one recommendation. This kind of engine oil is designed for delivering the highest level of protection for two-cycle engines.

Step 5: Mix the correct weed eater oil to gas ratio for your two-cycle engine.  Most are either 40:1 or 50:1 gas-to-oil ratios.  Realistically, you won’t kill an engine if you get the wrong mix ratio (as you will eventually running it on non-oiled gas).  Still, it’s best to get the ratio right.

Weed Eater Oil To Gas Ratio

If you are mixing a 40:1 gas-to-oil ratio, mix 3.2 U.S. ounces of oil for every 1 gallon of gas you need.

If you are mixing a 50:1 gas-to-oil ratio, mix 2.6 U.S. ounces of oil for every gallon of gas you need.

Step 6: First pour the oil into the gas can. After, add the gasoline at the right mix ratio. Once done, you can close the fuel canister. Do not forget to shake the canister by hand to get them completely mixed.

Step 7: Don’t go overboard on how much fuel you mix.  Mix only enough gasoline that you will use in your engine in the next three months. If you need to store oiled gas longer, there are additives you can use, but they aren’t cheap.

I hope this is helpful.  If you have questions, please leave them below.

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2 Responses

    1. John, it depends on the size of your tank. Check your manual for both the tank size and fuel-oil mixture ratio, and act accordingly.

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