How to Mix Oil and Gas for 2-Cycle Engines

Honda EM5000IFrom older snowblowers to modern chainsaws and blowers, two-cycle engines are one of the most common ways to effectively and efficiently power and lubricate modern landscaping equipment. These engines are unique, however, because they require a mixture of fuel and oil in order to operate properly and without major damage. Conversely, four-cycle engines require separate chambers of oil and fuel to be sufficiently filled prior to operation. This means equipment owners with a two-cycle engine will need to get familiar with proper mixing ratios and procedures before they get the job done with the equipment outdoors.

Why Do Two-Cycle Engines Require a Mixture of Fuel and Oil?

The unique design of a two-cycle engine means that its crankcase isn’t sealed off, like it would be if the engine were a four-stroke design instead. This means that the gas-and-oil mixture created by the equipment owner flows into the crankcase first, and then flows into the engine’s combustion chamber. Essentially, the mixture is responsible first for lubrication, and later for ignition and combustion. If oil or fuel is missing from this mixture, the engine can smoke, lock up, refuse to start, or require a serious amount of maintenance.

This design was largely made specifically for equipment with smaller engines, or equipment that was simply used less often. IT was also an exceedingly inexpensive design compared to four-stroke engines for several decades. While that reality has changed, plenty of older snowblowers, and virtually all smaller power equipment tools, still utilize two-stroke engines to get the job done. Equipment owners, therefore, need to know how to properly mix a solution and what the dangers are of improperly blending fuel and oil prior to operation.

A Look at the Dangers of an Improper Fuel-to-Oil Ratio

Engine manufacturers pair their products with very specific and stringent guidelines for mixing oil with fuel, and that’s for good reason. When the improper ratio is used with two-cycle engines, they can suffer from problems as minor as smoking to issues as major as major engine damage, failure, and required replacement. Before mixing oil and fuel for one of these engines, consider the three major pitfalls of using a bad ratio:

1. Smoky Engine Starts and Excessive Fumes

Too much oil in a two-cycle engine mixture can cause the engine to smoke, since it’s actually trying to burn the oil as fuel. Oil just doesn’t work, however, and all this process will accomplish is an excessive amount of smoke and toxic emissions.

2. Engine Damage Due to Lack of Lubrication

On the other end of the equation, the lack of a sufficient amount of oil can lead to real engine damage after even a short period of use. Without the proper amount of oil in the mixture, equipment owners will be doing something akin to driving a car with dangerously low oil levels. The engine can lock up, burn up, and require expensive replacement in a matter of moments.

3. Failure to Properly Start

Finally, an improper mixture can make it impossible for the engine to start at all. That means a full drain of the fuel container and a second attempt at getting the mixture right.

How to Create a Proper Fuel and Oil Mixture for Two-Cycle Engines

To get the job done, a few simple steps are required. Whether it’s separating the fuel from the oil initially, or mixing them properly when the engine requires refilling, here’s what to know in order to avoid smoke, engine damage, or failed engine starts.

1. Separate Fuel from Oil

Don’t go into autopilot and mix an entire gas can’s worth of fuel and oil. This opens up a range of opportunities for error that can lead to engine damage, and it can mean real monetary loss because oil and gas cannot be separated once they’re mixed together. Keep oil and gas in separate gas cans and mix only when needed.

2. Have Extra Oil, or a Bulk Amount, Available

Especially in the case of snowblowers, having extra oil on hand just makes sense. After all, how many people are able to make a quick run to the local home improvement store for oil after a major winter storm? Keeping extra oil on hand is convenient, and buying oil in bulk is often far more affordable than buying it one container at a time.

3. Know the Proper Ratio and Mix When Needed

Typically, engine fuel and oil mixtures fall into one of two major ratios. Most manufacturers require either a 40:1 or 50:1 mix, and this information is specified in the engine’s user manual. Verify the ratio and then mix accordingly prior to each refueling of the engine.

For Parts, Oil, and Pre-Mixed Solutions, Visit

Whether it’s a bulk supply of oil, a selection of pre-mixed solutions for two-cycle engines, or the OEM parts needed for engine maintenance and service, Ralph Helm, Inc. has exactly what buyers need to keep any equipment purchase in great condition for years to come.

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