Most Husqvarna string trimmers use a 2-cycle small engine. However, Husqvarna has introduced models with 4-cycle engines to the market as well.
Knowing the type of engine on your trimmer and using the right fuel will keep you from damaging the engine or causing other fuel-related issues.
Husqvarna string trimmers with 2-cycle engines require a gas-to-oil mixture at a ratio of 50:1. Use unleaded gasoline with a minimum 89-octane rating and a maximum ethanol content of 10%. A premium 2-cycle engine oil must be mixed with the gas before adding it to the fuel tank.
Husqvarna string trimmers with 4-cycle engines will have separate fill ports. One for unleaded gasoline with a minimum 89-octane rating and maximum ethanol content of 10%. The other is for an SAE 10W-40 engine oil.
If you are unsure what type of engine you are running on your trimmer, refer to your operator’s manual.
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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
When problems develop in your string trimmer, old or wrong fuel is often the underlying cause of the problem. It can cause the trimmer to lose power, bog down, die, or not even start.
Gas can begin to break down and become less effective as quickly as 30 days after purchase. Ethanol, an alternative fuel added to gas, is not friendly to the small engine on a trimmer.
This is because ethanol naturally attracts moisture to the fuel system. This moisture and ethanol mixture will leave behind varnish and sticky deposits that may restrict fuel flow and cause component failures.
This mixture will also separate from gas over time which may cause the engine to extremely run hot when it is burned.
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 String Trimmers:
To avoid the negative effects ethanol has on an engine, you may choose to use an ethanol-free fuel. You can find these fuels online and at your local hardware store.
Husqvarna offers an XP Pre-Mix for a 2-cycle engine that is already mixed at a fuel-to-oil ratio of 50:1. You can also find 4-cycle fuel in canisters for a 4-cycle string trimmer.
These fuels are a convenient option to store on the shelf so they are ready when you need them. However, these are the most expensive options to fuel a trimmer.
Gas and Oil to Use in a 2-Cycle Engine
2-Cycle Gas and Oil Mix
All 2-cycle 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 Husqvarna 2-cycle string trimmer requires a gas and oil mixture at a ratio of 50:1. This means 50 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 fuel tank.
You can use the manufacturer’s recommended XP synthetic 2-stroke engine oil. Another alternative is this 2-cycle mix by Kawasaki. It comes in 5.2 oz. and 6.4 oz. bottles that can be mixed with 2 gal. or 2.5 gal. of gas respectively for a 50:1 mix.
2-Cycle Husqvarna Gas-to-Oil Mix
| Gas to Oil Mix Ratio | 1 Gallon Gas | 2 Gallon Gas | 2.5 Gallon Gas |
|---|---|---|---|
| 50:1 | 2.6 oz Oil | 5.2 oz Oil | 6.4 oz Oil |
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 the fuel tank.
You can find a 50:1 premixed cans of fuel at your local hardware store or online.
Gas and Oil to Use in a 4-Cycle Engine
Gas for 4-Cycle String Trimmer
While 2-cycle trimmers have been on the market for many years, you will now find 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 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 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 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.
Husqvarna recommends SAE 10W-40 engine oil.
4-Cycle Husqvarna Engine Oil Viscosity
| Manufacturer | Engine Oil |
|---|---|
| Husqvarna | 10W-40 |
In Summary
The fuel used in your string trimmer affects its performance. When fuel ages, it can cause corrosion and fuel restrictions. Follow these simple steps when choosing a fuel for your trimmer:
- Always use fresh gas.
- Make sure the gas contains no more than 10% ethanol.
- Know the type of engine on your trimmer (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.
- Store gas in a dry location away from moisture and combustible products.