What Is Husqvarna 240 Fuel Mix Ratio (50:1 Mixing Specs)

The Husqvarna 240 uses a 50:1 mix: 50 parts fresh unleaded gasoline to 1 part air-cooled two-stroke oil. That means 2.6 US fluid ounces of oil per US gallon of gas, or 100 milliliters per 5 liters. Measure carefully, use fuel that meets the manual’s requirements, and never run the saw on straight gasoline.

Getting the ratio right is a simple step that helps protect the saw’s engine and lets you work with more confidence. The key is to measure the gasoline and oil accurately, then keep bar-and-chain oil in its separate reservoir. Below, I’ll explain the Husqvarna 240 fuel mix, show common batch sizes, and cover checks that matter before starting.

Husqvarna 240 Fuel Mix, Bar-and-Chain Match, and Safety Setup

The fuel ratio tells you how much two-stroke oil to add to gasoline. For the Husqvarna 240, the specified ratio is 50:1. This is separate from bar-and-chain oil, which goes in its own tank to lubricate the cutting parts.

How much two-stroke oil does a Husqvarna 240 need?

A 50:1 ratio means 50 equal parts gasoline for every 1 equal part two-stroke oil. For simple measuring, use 2.6 US fluid ounces of oil for each US gallon of gasoline, or 20 milliliters for each liter of gasoline.

These figures measure oil against the gasoline amount. They do not mean oil should make up 2% of the finished fuel’s total volume. For example, measure 5 liters of gas, then add 100 mL of oil.

I teach owners to choose a batch size they can measure accurately and use while the fuel is fresh. A smaller, carefully measured amount is better than guessing at a large batch. Use Husqvarna-branded or equivalent high-quality oil made for air-cooled two-stroke engines. Do not substitute four-stroke engine oil.

What gasoline and container should you use?

Use fresh, clean unleaded gasoline that meets the octane requirement in the manual for your saw. The guidance for this model is not to exceed E10, which is gasoline containing up to 10% ethanol. If the fuel label or pump information is unclear, check the fuel and saw manuals before filling.

Mix the fuel in a clean, approved fuel container. Add the measured gasoline and oil, close the cap, and shake the container to blend them. Label it clearly as two-stroke fuel so it is not mistaken for straight gasoline. Do not mix or fuel near flames, sparks, or other ignition sources.

Does the bar or chain change the fuel ratio?

No. The 50:1 fuel mix stays the same regardless of bar length or chain type. The Husqvarna 240 is about 38.2 cc and is commonly supplied with a 16-inch bar, but available setups can vary by market and model revision.

A common setup uses 3/8-inch low-profile pitch and .050-inch gauge. Pitch and gauge must match the bar, chain, and saw; drive-link count also depends on the bar. Check the markings on your bar and chain, then confirm the match in the manual. Do not assume that every 16-inch bar takes the same chain.

Safe Field Cutting and Landscaping Operation

Correct fuel is only one part of safe operation. Before starting, inspect the saw and work area, follow the model’s starting instructions, and use proper protective gear. Fuel the saw outdoors with the engine cool, and keep the chain brake engaged during starting.

What should you check before starting?

Wear chainsaw-rated eye and hearing protection, a helmet where appropriate, chainsaw-protective legwear, gloves, and suitable boots. Check that the chain brake, throttle lockout, chain catcher, fasteners, bar, chain, and controls are in good condition. Make sure the chain is correctly tensioned and the cutting area has stable footing and a clear escape route.

Look for overhead hazards, nearby people, utilities, and wood that is hung up or under tension. Tree work can involve risks that are hard to judge from the ground. For felling or handling suspended or hung-up trees, use trained help and a suitable plan. Follow applicable rules, including OSHA 1910.266 or ANSI Z133 where they apply.

How do you fuel and start the 240?

With the engine off and cool, fill the fuel tank with the correctly mixed gasoline and two-stroke oil. Fill the separate oil tank with dedicated bar-and-chain oil. Do not put two-stroke fuel in the oil tank or bar oil in the fuel tank.

Start the saw on stable ground, using the cold- or warm-start steps in the manual for your model. Keep the chain brake engaged while starting. At idle, the chain should not move. If it does, stop and address the cause before cutting; do not try to compensate by guessing at carburetor settings. Use the exact idle and maximum-speed limits in the correct manual, not a generic RPM figure.

Check that oil reaches the chain using the method in the manual. Keep the bar pointed safely away from people and objects during any check. Oil delivery is not a user-set flow rate specified here, so do not adjust it based on a guessed target.

Chain Sharpening, Tension, and Saw Maintenance

A sharp, correctly tensioned chain helps the saw cut as intended. Chain care does not change the 50:1 fuel ratio, but it affects cutting performance and can help you spot a problem before work begins.

What chain settings should you verify?

Use the chain maker’s instructions for sharpening and depth-gauge settings. A depth gauge controls how much the cutter takes from the wood; 0.025 inch (0.65 mm) is common for compatible low-profile chain, but verify the chain type before setting it.

Check chain tension as directed in the saw manual. A chain that is too loose can come off, while one that is too tight can increase wear. Use bar-and-chain oil in the correct reservoir, and keep the bar groove and oil passages clear of chips. Do not force a dull chain through wood, and never cut above shoulder height.

What should you do if the saw runs poorly?

Stop using the saw if it runs unusually hot, loses power, surges, or behaves abnormally. Straight gasoline, too little oil, degraded fuel, or a leak in the intake or fuel system can lead to poor lubrication or an excessively lean running condition. These problems can overheat the engine and may cause severe damage.

Do not try to fix a suspected fuel or carburetor problem by turning adjustment screws without the correct instructions and tools. Confirm the fuel mix first. If the symptoms continue, have the saw inspected before restarting it.

Fuel Storage, Off-Season Care, and Restarting

Fuel quality can change during storage, so prepare only what you expect to use and follow the fuel and oil makers’ storage guidance. Before putting the saw away, shut it off, let it cool, and clean it. Check the manual for model-specific storage and restart steps.

How should you store mixed fuel?

Keep mixed fuel in a clearly labeled, approved container with the cap closed. Store it away from heat, flames, sparks, and living areas, in line with local rules and the container label. Do not rely on a universal storage period: fuel life depends on the fuel, oil, storage conditions, and any stabilizer used. Follow the product labels and the saw manual.

Before restarting after storage, inspect the saw and check that the fuel is suitable for use. If it is stale, contaminated, or of uncertain age, do not put it in the saw. Use fresh fuel mixed at 50:1 instead.

After each use, engage the chain brake, shut off the engine, and let the saw cool before cleaning or refueling. Remove chips from the cover, brake area, bar groove, and oil passages. Check for chain damage and correct tension, then refuel only away from ignition sources.

Common questions about Husqvarna 240 fuel mix

What is the fuel mix ratio for a Husqvarna 240?
Use 50 parts gasoline to 1 part high-quality air-cooled two-stroke oil.

How much oil goes in 1 gallon of gas?
Use 2.6 US fluid ounces of two-stroke oil per US gallon of gasoline.

How much oil goes in 5 liters of gas?
Use 100 milliliters of two-stroke oil for 5 liters of gasoline.

Can I use 40:1 or 25:1 instead?
Do not substitute another ratio unless the manual for your exact saw directs you to do so. The specified ratio here is 50:1.

Can I use straight gasoline in the Husqvarna 240?
No. Straight gasoline lacks the two-stroke oil the engine needs and can cause severe engine damage.

Does bar-and-chain oil go in the fuel?
No. Put bar-and-chain oil in its own reservoir. Use two-stroke oil in the gasoline.

Can I use gasoline with ethanol?
The guidance here is not to exceed E10. Follow the fuel requirements in your model’s manual.

Does changing the bar length change the fuel ratio?
No. The fuel ratio remains 50:1. The bar and chain still need to match the saw and each other.

What if the chain moves while the saw idles?
Stop the saw and check the manual or seek qualified service. Do not continue cutting or guess at a carburetor adjustment.

What if I am unsure whether my fuel is fresh?
Do not use fuel that is stale, contaminated, or of uncertain age. Mix a fresh batch at 50:1.

(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)