Which oil for two-stroke engines should you choose?

In a two-stroke engine, the mixture combustion process takes place in a slightly different way than in a four-stroke unit. This, in turn, means that the engine oil used here differs significantly in composition and mode of action from its four-stroke counterpart. How does this oil work and what should it consist of?

How oil works in a two-stroke engine

Two-stroke power units are characterized by simplicity and lightweight construction. They do not have a separate lubrication system, so oils for two-stroke engines are added directly to the fuel (usually in a 1:50 ratio). Thanks to this, it flows through the interior of the engine and crankcase, creating an oil film on their surface, which protects them against excessive wear due to friction and corrosion.

What should two-stroke oil consist of?

Standard oil for two-stroke engines consists of:

1. Functional additives designed to reduce flammability and improve oil purity. Unfortunately, they cause more smoke and block the piston to some extent. And that is why their percentage content in the oil is negligible.
2. Base oils, which improve the lubricity of the oil, but also block the piston, reduce cleanliness and increase exhaust smoke.
3. A solvent, whose task is to increase the ability of the oil to mix with the fuel. The purpose of this substance is also to reduce the ignition temperature of the oil. This means that adding another solvent may cause an engine cooled, for example by air, to generate a higher risk of ignition. An important function of the solvent is to reduce smoke, thanks to which combustion products have a smaller impact on the environment.
4. PIB — this is an ingredient whose task is to improve the lubricity of the oil and reduce smoke. This ingredient means that two-stroke engines do not emit so many pollutants into the atmosphere. It is the second largest component of oils (after the base oil) in terms of content.

Type of oil and engine cooling technology

The type of oil used also depends on the way the engine is cooled. Basically, there are two types of oils that are intended for air- or water-cooled units.

1. Oil for an air-cooled two-stroke engine — it is primarily a low-ash product. The low ash content prevents the oil from igniting at higher operating temperatures. It is true that the ashes mentioned tend to accumulate inside the exhaust system, but they are effectively blown outside, so the system remains unobstructed.
2. Oil for a water-cooled two-stroke engine — it is primarily a product that does not contain ash. Thanks to this, they do not settle in the exhaust system even when the temperature of the drive unit is relatively low (limited by water cooling). Otherwise, there would be a risk of the system losing its patency at low temperatures.

To sum up, low-ash oils are used to lubricate the most popular two-stroke drive structures (air-cooled) because they are less susceptible to ignition. And these oils are worth recommending to users of two-stroke machines.