Because running the wrong fuel mix or old gas can affect your string trimmers performance, it’s important to choose the right fuel and mix it properly.
DeWalt string trimmers use a gas and oil mixture at a ratio of 50:1. It requires an unleaded gas with a minimum 89-octane rating and a minimum 10% ethanol content. Mix gas with premium 2-cycle engine oil.
Be careful mixing and adding fuel to the fuel tank. A hot fuel tank can be under pressure. Allow the trimmer to cool down for a few minutes before slowly removing the cap.
This post may include affiliate links. Purchases made through these links may provide a commission for us, at no extra cost to you. As an Amazon Associate, we earn from qualifying purchases.
Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
Old or Bad Gas in a DeWalt String Trimmer
Gas is often the root cause of a running problem. Allowing gas to sit in your DeWalt string trimmer for long periods can cause component wear and fuel restrictions.
Gas begins to oxidize and break down as soon as 30 days after purchase. Most gas is blended with ethanol. This is an alternative fuel added to make gas more environmentally friendly.
While ethanol may be better for the environment, this product is not good for the small engine on your string trimmer. This is because ethanol attracts moisture to the fuel system.
Water and ethanol will separate from gas and leave behind varnish and deposits that can cause fuel passageways to clog. This will cause the trimmer to gun sluggish and possibly die or not even start.
Because gas begins to go bad so quickly, it’s important to use fresh fuel and consume it within 30 days. If you are unable to consume it this quickly, add a fuel additive like Sea Foam Motor Treatment or STA-BIL.
This product will stabilize your gas and reduce moisture so it lasts a little longer. I add it to every tank of fuel on my small engine equipment.
DeWalt string trimmers require unleaded gasoline with a minimum octane rating of 89 and a maximum ethanol content of 10%. Mix a 2-cycle premium oil with the gas before adding it to the fuel tank.
Gas and Oil to Use in a 2-Cycle DeWalt String Trimmer
2-Cycle Gas and Oil Mix
DeWalt string trimmers require a 2-cycle premium oil to be mixed with gas before adding it to the fuel tank. Don’t add straight gas to your 2-cycle string trimmer.
Gas runs extremely dry so adding straight gas will cause the engine to seize. Without the lubrication provided by the addition of oil to the gas, the internal parts of the engine won’t be able to move freely.
Most likely, if you accidentally add straight gas to your DeWalt string trimmer and start it, you will have to replace it with a new trimmer. The engine may be damaged beyond repair.
DeWalt 2-cycle string trimmers use a gas and oil mixture at a ratio of 50:1. This means you must mix 50 parts gas with 1 part oil. Refer to the chart below for the amount of oil required to be mixed with common gallon measurements.
When creating this mix, use unleaded gasoline with a minimum octane rating of 89 (mid-grade) and maximum ethanol content of 10%. Add a 2-cycle premium engine oil that is ISO-L-EGD and JASO M345 FD certified.
Note: Do not add regular engine oil. 2-cycle oil is different from regular engine oil.
How to mix gas and oil for a 2-cycle string trimmer:
- Use the chart below to determine how much fuel mix to prepare.
- Remove the cap from an approved gas can. Add unleaded fuel (minimum 89 octane rating & maximum 10% ethanol content) to a gas can.
- Refer to the chart below for the ounces of oil required. Add the 2-cycle oil to the gas can.
- Replace the cap.
- Gently shake the fuel and oil until they are mixed.
- Add to the DeWalt string trimmer’s fuel tank.
Kawasaki offers a good 2-cycle engine oil that comes in a 2.6 oz bottle to be mixed with one gallon of gas to create the 50:1 mix required.
2-Cycle String Trimmer Gas-to-Oil Mix
|Gas-to-Oil Mix Ratio
|1 Gallon Gas
|2 Gallon Gas
|2.5 Gallon Gas
|2.6 oz Oil
|5.2 oz Oil
|6.4 oz Oil
2-Cycle Premixed Ethanol-Free Fuel
The best type of fuel to use in a DeWalt string trimmer to reduce fuel problems and extend engine life is an ethanol-free fuel mix. This is an ethanol-free blend of oil and fuel that is ready to pour into your DeWalt string trimmer’s fuel tank.
You won’t have to deal with the bad effects of ethanol as discussed in the fuel section. ECHO and Husqvarna offer a 50:1 premixed fuel that can be purchased online or at a local hardware store near you.
The fuel used in your DeWalt string trimmer not only affects performance but also affects the likeliness problems develop in the fuel system and engine. Follow these simple tips when choosing a fuel for your string trimmer:
- Always use fresh gas.
- Make sure the gas contains no more than 10% ethanol.
- Choose gasoline with a minimum 89-octane rating.
- Use a 2-cycle gas and oil mixture at a ratio of 50:1.
- Add a fuel stabilizer so your gas lasts longer without breaking down. The length of time fuel is kept stable varies. Read the label and don’t assume fuel additives keep fuel stable for long periods. Consume gas within 90 days when using a stabilizer unless the additive manufacturer states differently.