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Gas & Oil for Troy-Bilt String Trimmers (2-Cycle & 4-Cycle)

Most Troy-Bilt string trimmers use a 2-cycle small engine. However, Troy-Bilt has introduced models with 4-cycle engines to the market as well.

Knowing the type of engine on your Troy-Bilt and using the right fuel will keep you from damaging the engine or causing other fuel-related issues.

  • Troy-Bilt string trimmers with 2-cycle engines require a gas-to-oil mixture at a 40:1 ratio.
    • Use unleaded gasoline with a minimum 89-octane rating and a maximum ethanol content of 10%.
    • Add a premium 2-cycle engine oil.
    • Mix gas and oil before adding them to the fuel tank.
  • Troy-Bilt string trimmers with 4-cycle engines have separate fill ports.
    • One fill port for unleaded gasoline with a minimum 89-octane rating and maximum ethanol content of 10%.
    • One fill port for an SAE 30 engine oil.

If you are unsure what type of engine you are running on your Troy-Bilt string trimmer, refer to your operator’s manual. Always refuel in a well-ventilated area away from combustible products.

Fuel tank on a Troy-Bilt String Trimmer

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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 Troy-Bilt String Trimmer

It’s important to use the right gas and consume it quickly. Gas is often the primary reason a Troy-Bilt string trimmer has starting and running issues.

This is because gas can begin to break down and become less effective as soon as 30 days after purchase. Most gas contains ethanol that attracts moisture to the fuel system.

Water and ethanol will separate from gas leaving behind varnish and deposits that result in corrosion and fuel restrictions in the fuel system.

Because of its negative effects, never use gas with an ethanol content greater than 10%.

Use Fresh Fuel and a Fuel Stabilizer:

Because gas breaks down quickly, it is important to purchase fresh gas and consume it within 30 days. Add a fuel additive like Sea Foam Motor Treatment to stabilize the gas and reduce moisture so it lasts a little longer.

Note: Some 2-cycle engine oils include a fuel stabilizer. Don’t assume it will keep your fuel stable longer than 30 days unless stated by the manufacturer.

Fuel stabilizers cannot reverse the effects of old fuel. Add fuel stabilizers to fresh gasoline.

Use of Ethanol-Free Fuel for Troy-Bilt String Trimmers:

To avoid the negative effects ethanol has on a Troy-Bilt engine, you may choose to use an ethanol-free fuel. You can find these fuels sold online or at the fuel pump from select fuel stations.

Gas and Oil to Use in a 2-Cycle Troy-Bilt String Trimmer

2-Cycle Gas and Oil Mix in a Troy-Bilt String Trimmer

All 2-cycle Troy-Bilt string trimmers require a 2-cycle premium oil to be added to gas before adding it to the fuel tank. Don’t make the mistake of adding straight gas to your 2-cycle string trimmer.

This will cause the engine to seize up and no longer run. This is because gas runs very dry. 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 string trimmer and start it, you will have to replace it with a new one. The engine will be damaged beyond repair.

Your Troy-Bilt 2-cycle string trimmer requires a gas and oil mixture at a ratio of 40:1. This means 40 parts gas is mixed with 1 part oil. Refer to the mixing chart below.

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 oil that is ISO-L-EGD and JASO M345 FD certified.

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.
  • Using the chart for 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 Troy-Bilt string trimmer’s fuel tank.

You can use a good 2-cycle engine oil like this one from Briggs & Stratton or MTD. The 3.2 ounce bottles must be mixed with 1 gallon of gas.

2-Cycle Troy-Bilt Gas-to-Oil Mix

Gas to Oil Mix Ratio1 Gallon Gas2 Gallon Gas2.5 Gallon Gas
40:13.2 oz Oil6.4 oz Oil8.0 oz Oil
Troy-Bilt 2-Cycle Gas-to-Oil Mix Ratio

2-Cycle Premixed Ethanol-Free Fuel

A great option to reduce fuel problems and extend engine life is using an ethanol-free fuel mix. This is an ethanol-free blend of oil and fuel that is ready to pour into your Troy-Bilt string trimmer’s fuel tank.

You can find a 40:1 premixed can of fuel at your local hardware store or online.

Gas and Oil to Use in a 4-Cycle Troy-Bilt String Trimmer

Gas for Troy-Bilt 4-Cycle String Trimmer

While 2-cycle Troy-Bilt string trimmers have been on the market for many years, you will now find Troy-Bilt string trimmers with 4-cycle engines. These types of engines have separate ports for fuel and oil so there is no need to mix fuel and oil.

4-cycle Troy-Bilt string trimmers require unleaded gasoline with an octane rating of 89 or higher and an ethanol content of 10% or less.

It is best to add a fuel stabilizer like Sea Foam or STA-BIL to keep the gasoline from breaking down quickly and to help reduce moisture and gummy deposits in the fuel system.

While using gasoline with a low ethanol content is acceptable, it is not the best option available.

The best fuel to use in a Troy-Bilt string trimmer is an ethanol-free fuel available at the fuel pump at select fuel stations or in canisters at your local hardware store or online.

Ethanol-free gas is the more expensive choice. Purchasing in canisters is not only convenient, but it may also be a good alternative if you don’t want to deal with the potential headaches that can come from running old ethanol-based gas through a string trimmer.

Engine Oil in a 4-Cycle Troy-Bilt String Trimmer

4-cycle engines have separate fill ports for the engine oil and the fuel. DO NOT mix the oil and fuel together for a 4-cycle engine. Never use 2-cycle oil in a 4-cycle string trimmer.

Oil is required to keep the engine components lubricated. When the wrong type or not enough oil is used, friction can build in the engine and overheat causing your string trimmer not to start and possibly ruin the engine.

Troy-Bilt recommends SAE 30 air-cooled engine oil.

4-Cycle Troy-Bilt Engine Oil Viscosity

ManufacturerEngine Oil
Troy-BiltSAE 30
Engine Oil for 4-Cycle Troy-Bilt String Trimmers

In Summary

The fuel used in your Troy-Bilt string trimmer affects performance. When fuel ages, it can cause corrosion and fuel restrictions. Follow these simple steps when choosing a fuel for your Troy-Bilt string trimmer:

  • Always use fresh gas.
  • Make sure the gas contains no more than 10% ethanol.
  • Know the type of engine on your Troy-Bilt (2-cycle or 4-cycle).
    • 2-cycle: Mix gas and oil together before adding to the fuel tank.
    • 4-cycle: Use straight gas.
  • Add a fuel stabilizer so your gas has a longer shelf life without breaking down. Mix with fuel before adding to the fuel tank.
  • Store gas in a dry location away from moisture and combustible products.