Two-stroke mix for a gas trimmer

Use the gasoline-to-oil ratio specified in your trimmer’s owner’s manual or on the machine’s label. Many two-stroke gas trimmers use a 50:1 mix, but that ratio is not universal—using too little oil can damage the engine, while an incorrect mix can cause smoke or poor running.

Find the correct mix ratio

Look in the manual, on the trimmer’s fuel-cap area, or on a label on the engine. Confirm that the instructions are for your exact model. Don’t choose a ratio just because it is common or because the oil bottle recommends it; the trimmer manufacturer’s specification takes priority.

A ratio such as 50:1 means 50 parts gasoline to 1 part two-stroke oil, measured by volume. For one US gallon of gasoline, that is about 2.6 US fluid ounces of oil.

Measure for the amount of gasoline you’re actually mixing. Use a marked fuel-mixing container or a measuring device intended for small liquid quantities; don’t estimate by pouring. If the manual specifies a different ratio, follow it rather than this table.

Choose the right fuel and oil

Use two-stroke oil intended for the type of engine specified by the trimmer manufacturer. A two-stroke trimmer needs oil mixed into its gasoline; four-stroke equipment generally has a separate oil reservoir and should not receive premixed fuel unless its instructions say otherwise.

Check the manual for the required gasoline grade and any limits on ethanol content. Do not use E15 or E85 unless the manufacturer explicitly approves it. Use fresh fuel and follow the manufacturer’s directions for how long a mix may be stored.

Mix fuel safely

1. Work outdoors or in a well-ventilated area, away from flames, sparks, and hot surfaces.
2. Use a clean, approved fuel container. Add the measured gasoline and the correct amount of two-stroke oil according to the container or oil-maker’s mixing directions.
3. Close the container and mix thoroughly. Label it with the ratio and date, then store it as directed by the trimmer manufacturer and local fire-safety rules.
4. Refuel only when the trimmer is switched off and cool. Wipe up spills before starting it.

Do not mix fuel in the trimmer’s tank, and never run the engine indoors. Follow the owner’s manual for handling, storage, and disposal.

If you used the wrong ratio

If you added too little oil, don’t run the trimmer. Drain the fuel into an approved container and prepare a fresh batch at the specified ratio. If you added too much oil, the mix may cause smoke, fouled spark plugs, or rough running; draining it and mixing a correct batch is safer than trying to correct the tank by guesswork.

If the trimmer has already run on the wrong mix and now runs poorly, stop using it and consult the manual or a qualified small-engine service professional. Persistent trouble after correcting the fuel may require inspection for engine damage or a fouled plug.