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How to Add Two-Stroke Chainsaw Oil, step by step

The chainsaw is a handy piece of garden equipment that can help you in felling, limbing, and pruning your garden. Portable chainsaws can either be cordless or gas-powered, with the latter being an excellent alternative when high performance and cutting speed are desired. However, the utility of gas-powered chainsaws is directly related to their maintenance. Speaking of maintenance, the most crucial step is selecting and adding the right kind of lubricant oil for your chainsaw to maximize its service life. In two-stroke chainsaws, oil and fuel are mixed and then added to the engine. If you are looking for some guidelines before lubricating your chainsaw’s two-stroke engine, then this blog post might answer some of your questions.

How to add two-stroke chainsaw oil, step-by-step:

  • Step 1: Find a suitable fuel container that is clean and free from any deposits.
  • Step 2: Select the right kind of fuel for use in your chainsaw engine and add it into the container.
  • Step 3: Choose the appropriate oil type. The most common types in two-stroke engines are high-performance (HP) oils and low smoke (LS) two-stroke oils.
  • Step 4: Mix the oil and fuel in the appropriate proportion in the container. The general guideline suggests a 50:1 fuel to oil ratio.
  • Step 5: Add the premix into the engine. Secure its cap tightly.

For further elaboration on these steps, we recommend that you keep reading this article.

What Are Two-Stroke Engines?

In automotive terminology, a stroke is defined as the piston’s movement from the top dead center to the bottom dead center in the engine’s cylinder. In two-stroke engines, the entire power generation cycle is completed in two strokes of the piston or one crankshaft revolution.

This type of build reduces the number of moving parts and, ultimately, the weight of the engine. Compared to four-stroke engines, two-stroke counterparts generally provide a better power-to-weight ratio and require less maintenance. However, they are not very effective in controlling emissions and are quite noisy as well. Their use is limited for smaller applications where less load is desired, such as chainsaws, hedge trimmers, and dirt bikes. In contrast, four-stroke engines are used in lawnmowers, pressure washers, and automobiles.

Lubrication, Why Is It Important?

An engine consists of a sliding piston mechanism connected to the crankshaft. These parts, particularly the piston, are sliding at a very high velocity while making contact with the cylinder walls. The friction between the parts and the cylinder walls generates enough heat to cause the parts to fuse, causing a seizure. Furthermore, the parts wear at an accelerated rate at such high friction.

It becomes necessary to introduce a lubricant that reduces friction between the parts of an internal combustion engine.  The lubricant ensures that the parts slide over each other at a reduced wear rate. It also prevents the engine from reaching excessively high temperatures and increases engine components’ service life.

Lubrication of Two-Stroke Engines:

Two-stroke engine lubrication is different from that of a four-stroke engine. There are valve trains, camshafts, timing gears, and pushrods in four-stroke engines, whereas, in two-stroke engines, these parts are absent. Due to its highly sophisticated design, a four-stroke engine uses a separate oil reservoir to lubricate these parts. In comparison, a two-stroke device doesn’t require a separate oil reservoir. Oil and gasoline are mixed and then added to a two-stroke engine. The proportion of the oil-fuel mixture is quite crucial and is discussed in the next section.

Lubricating a Two-Stroke Engine, Step-by-Step:

Lubricating your engine is the most crucial maintenance step. Neglecting the engine lubrication not only hampers the performance and productivity of your engine but is also detrimental to the engine’s service life. This next section will provide an in-depth guide about two-stroke engine lubrication, from choosing the optimum oil type to making the correct oil-fuel mix.

Step 1: Choose A Suitable Fuel Container:

For better engine performance, the added fuel should always be clean. Dirty fuel cans are a leading cause of fuel contamination. Most fuels oxidize in the presence of air to form sticky deposits that can clog the jets and fuel lines of your chainsaw. Moreover, the presence of oil attracts dirt and debris, which further adds to the contamination.

Fuel jerry cans can be an excellent option for creating oil-fuel mixes as they are cheap and less prone to get dirty. If you already use a can for mixing, make sure that it is adequately cleaned and devoid of any debris contaminating the mixture.

Step 2: Select the Right Fuel Type:

Various fuel types are available for use in a two-stroke engine. However, you should be aware of each fuel type and its corresponding compatibility with oil types. This information is summarized in the following table.

Fuel Type
Ethanol Blended (E10)
Regular (Unleaded)
Open Fuel
Premium High Octane (Unleaded)
Recommended and approved for use in all chainsaw engines
Recommended and approved for use in all chainsaw engines
May be used in chainsaw engines
Not recommended for use in chainsaws
Oil Conditions
Only HP two-stroke oil should be used
Low smoke (LS) two-stroke oil is recommended. HP two-stroke oil can be used
Only HP two-stroke oil should be used

Step 3: Find the Right Oil:

We need to find a suitable oil type for two-stroke chainsaw engines with the proper fuel selected. Listed below are the various classes of two-stroke engine oils available in the market. Based on your application and preferences, you can choose either of the types.

– High Performance (HP) Two-Stroke Oil:

Among the modern synthetic oils, the HP two-stroke oil has been instrumental for the high performance of the two-stroke motor and garden power tools. It is designed to work well with low-quality fuels. HP oils keep the engine clean and prevent the formation of coatings on the cylinder walls and crankcase and prevent ring sticking. This oil type is suited for use in small to medium-sized water-cooled engines. Husqvarna and Stihl are the most common manufacturers of such oils.

– Low Smoke (LS) Two-Stroke Oil:

Husqvarna produces the low smoke (LS) two-stroke engine oil, a mix of synthetic and mineral oils. This oil type provides reasonably low smoke emissions from the engine. It also lowers the engine’s peak temperature, thereby improving the components’ service life. The formulation in LS oils prevents piston seizures by improving the lubrication between piston and cylinder walls.

As a precaution, never use two-stroke oils recommended for water-cooled engines in a non-water-cooled engine, also known as outboard engines. Also, be wary of not using oil from a four-stroke engine.

– Mineral Oil:

Mineral oils are the opposite of fully synthetic oils as they are derived from petroleum. They cost relatively less than their synthetic counterparts and provide good lubrication. However, compared to synthetic oils, their cleanliness is on the lower side as their prolonged use can leave gummy deposits in the engine that can cause declines in its performance and an increase in maintenance.

For this reason, manufacturers tend to mix additives such as detergents, stabilizers, and octane enhancers to provide a clean burn and improve the combustion properties of these oils. Such oils are known as semi-synthetic oils.

Step 4: Prepare the Fuel-Oil Mix:

With the oil and fuel selected, we are all set to create our oil-fuel mix, also known as premix or petrol, for our two-stroke engine. The proportion of oil and fuel is significant while you make the premix. Too much oil can make it difficult for the engine to start, and it may give off more smoke than usual. However, too little oil can decrease the lubrication, damaging the internal parts and raising the temperature.

– Finding the correct mixing ratio:

The mixing ratio is defined as the amount of fuel mixed with the amount of lubricant oil. To get the exact mixing ratio for your two-stroke engine, it is better to go through the owner’s manual of your chainsaw. The higher the mixing ratio, the less oil is needed for maintenance. Older and larger engines require a higher oil amount and thus need a low mixing ratio.

If you can’t find an exact number on your owner’s manual, you should remember a rule of thumb, which is 50:1. This means that you need to prepare a mixture of 5L fuel with 100 mL oil. This proportion is recommended if your two-stroke engine is up to 75cc.

For engines larger than 75cc, the ideal mixing ratio should be 33:1, meaning that your mixture should contain 152 mL oil mixed in 5L gasoline.

– Mixing the oil and fuel together:

While preparing the mixture, these are the steps you can follow:

  • Step 1: Add fuel to the container: Take the clean fuel storage container and fill it half with gasoline.
  • Step 2: Add oil to the fuel: Add the entire amount of 2-stroke oil in the container. For convenience, these oil bottles typically come in amounts that can be consumed entirely.
  • Step 3: Shake the mixture: Shake the container for 10-15 seconds to ensure that the oil and fuel mix with each other thoroughly.
  • Step 4: Add the remaining fuel: Now, add the appropriate proportion of gasoline in the container to ensure that our desired mixing ratio is achieved. Seal the container’s cap and shake it for another 10 seconds to ensure complete mixing of the oil and gasoline.

– Adding the premix to the engine:

Once the premix is prepared, it can be added to the engine quickly. For a clean and easy addition, please use a funnel in case the fuel container doesn’t have a hose. Begin adding the oil by opening the oil/fuel cap and pouring the premix completely. Once the container is empty, use a rag to wipe off any oil spills. The fuel-oil mixture has now been added to your engine, and it’s good to go for a run.

Final Remarks:

By and large, engine lubrication can never be ignored if a long-lasting product life is desired. While performing the oil addition, you should always make sure that you clean your fuel cap from any debris and always wipe off spills since they are essentially gasoline, which is highly combustible. If you intend to store your premix for future use, always keep the container airtight. Please manage a fuel stabilizer as it enhances the shelf life of gasoline. Always be sure to go through your manufacturer’s recommendations to find the right oil or fuel type for your device.