40:1 VS 50:1 (Which Oil Mixture Is Better For You)

Not using a proper oil mix ratio can cause your engine to run rich or lean! If you don’t mix enough oil, the engine will wear itself out and die. On the contrary, using too much oil will cause excessive emissions. 

So, which oil mixture should you use, 40-1 to 50-1 conversion

The 40:1 ratio has more oil compared to gas. That’s why 40:1 oil is slightly denser than 50:1 oil. This higher density helps with the lubrication of the engine. Because of that, the 40:1 ratio has better lubrication of the two. However, 50:1 oil has lower viscosity due to more gasoline which helps with 2-stroke engines. 

Anyways, there’s more to be discussed. Keep reading till the end to find all the information that you need. 

40:1 vs 50:1: Key Differences

First, we need to understand the ratio and how it affects your engine. This will make the comparison easier and you’ll easily figure out which one you require. 

That’s why we’ve made a small chart to better help you understand: 

Factors 40:1  50:1 
Oil Density Higher Lower 
Compatible Engine  4 Stroke 2 Stroke
Lubrication More  Less
Lubrication Speed Slower Higher
Viscosity Higher Lower
Ratio Per Gallon 3.2 oz of oil to every gallon of gasoline 2.6 fluid ounces of oil per gallon of gas

So, which one do you prefer after reading the chart? 

40-1 to 50-1 Conversion: Detailed Comparison

40-1 to 50-1 conversion

The chart was only a quick sneak peek. Now, let’s head to an in-depth comparison. 

1. Oil Density 

This portion is self-explanatory. Oil density means the percentage of oil in gasoline. 

40:1 oil means 40 units of gas and 1 unit of oil. So there’ll be 1 unit of oil in every 40 units of gas. If there are 500 units of gas, there will be 12.5 units of oil. 

That’s why 40:1 is a much better lubricator than 50:1 oil. We’re going to elaborate on that just a bit later. 

Likewise, there’s 1 unit of oil in every 50 units of gas in 50:1. This makes it thinner than 40:1 oil. Because of that, they can lubricate faster. 

Simply put, a 40:1 oil is denser than a 50:1 oil.


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2. Compatible Engine Type 

The first thing we’re going to talk about is the engine type. Because these two oil ratios can’t be used in all types of engines. 

There are mainly two types of engines based on engine strokes. The first type is a 2 stroke and the other is a 4 stroke. 

As the name suggests, a 4-stroke engine works in 4 unique stokes. This puts less pressure on the pistons due to less RPM and higher torques. 

That’s why 40:1 is a better choice for them due to higher oil density. It helps with the high torques of the 4-stroke engine. 

But in a 2 stroke engine, all the functions are done in two strokes. Obviously, they have a much higher RPM than 4-stroke engines. It eventually causes the piston to start degrading. 

That’s why they need faster lubrication. Because otherwise, pistons will move too much without lubrication (high RPM) and damage themselves. 

That’s why 50:1 oil is perfect for 2-stroke engines.


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3. Lubrication 

We’ve already talked about lubrication in the previous section. But there’s still something you need to know. 

A 4-stroke engine has an oil sump in the crankcase. This forbids the oil from getting mixed with gasoline. That’s why 4-stroke engines have better lubrication. 

For this reason alone, a 40:1 mix is a better lubricator for 4-stroke engines. 

On the contrary, a 2 stroke engine doesn’t have an oil sump in its crankcase. Therefore, oil in the mix of gasoline lubricates the engine. 

That’s why the 50:1 ratio does a better job. Because it provides gasoline while lubricating at the same time. 

4. Viscosity 

Viscosity represents the overall flow resistance of a liquid. In other words, the denser a liquid is, the slower it’s going to move. 

This is pretty self-explanatory. A mixture of 40:1 gas/oil will have more viscosity than a 50:1 ratio. 

Because of lesser viscosity, the 50:1 will travel faster. This helps with the 2 stroke engines as the pistons can wear out faster. 

On the contrary, the viscosity of 40:1 is ideal for 4-stroke engines. It needs more lubrication and the mixture provides more than enough. 

This will save your time and get you started right away! 

Final Verdict

Nowadays, synthetic oil has improved and offers better lubrication while having similar viscosity. So, 50:1 can be used in 4-stroke or older 2-stroke engines.

However, it’s always advised to use the ratio instructed by the manufacturer. It’s safe and no risks are involved. 

Frequently Asked Questions

Which is a richer mix 40:1 or 50:1?

40:1 is a richer mix due to 1 unit of oil for 40 units of gas. It’s also denser than 50:1 and has a slower flow. 

What is the mix for 50 to 1?

To achieve a 50:1 ratio, you have to add 2.6 oz of oil per gallon. Similarly, 3 gallons of gasoline will need 7.8 oz of fluid oil. 

Is it better to run lean or rich?

Running rich is better because running lean can destroy your engine permanently. Too much richness will also hurt the motor. 

Wrap Up 

That’s all we could explain on 40:1 vs 50:1. Hopefully, now you know how to mix the gasoline and oil properly. 

So, have you mixed up the gasoline yet? Tell us about your experience below! 

Finally, good luck!

Kevin Smith

2 thoughts on “40:1 VS 50:1 (Which Oil Mixture Is Better For You)”

  1. I agree. A lot of 2vstrokrs use 40:1. I have never seen a 4 stroke handheld chain saw. Not saying they don’t exist, but they couldn’t be common.

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