What Kind of Oil to Mix with Gas for a String Trimmer?

Have you ever tried putting normal gas in your weedeater? No worries. Every one has done it as some point in their life. When getting started with a weedeater, we often overlook the need to mix it with oil. But, now that you have learned from your mistake and know you need to mix your gas with oil, the question arises: what kind of oil to mix with gas for weedeater? There are multiple things you need to be aware of when mixing your weed eater gas. Check out Best Gas String Trimmer I Reviews of the Top Weed Whackers I 2018.

​Reasoning for the Oil

You may be asking yourself why oil is even needed for your weedeater. Well, mixing oil with your gas is very important to the overall operation of the weedeater. The oil is the only lubrication made available for the weedeater based on its design. Your weedeater uses a motor and just like your car, it needs to have oil for the lubrication. Without the proper amounts of oil, your weedeater will overheat, seize, and eventually stop working completely. This will only happen if you constantly neglect to add mixed gas in though.

​Fuel/Oil Mixing Ratio

​​One of the more important aspects of mixing your oil and gas is the ratio to use. Everyone has a different ratio, but there are a few that are superior. Common ratios are 32:1, 40:1, and 50:1. Every weedeater is made differently, thus, require different ratios. Looking over your operation manual that came with the weedeater. 

After determining the ratio to use, you should find it relatively easy to calculate the amount of oil ​and gas you need. Let's do the calculation for a 40:1 ratio weedeater. One gallon of oil is 128 ounces. Take this number and divide it by the amount of gasoline you need. In this case, the ratio is 40 gas to 1 gallon of oil. So, 128 / 40 will yield 3.2 ounces of gasoline needed.

Getting the Proper Fuel

Now that you know the amount of oil you will need, it is important to also know the type of gasoline needed. Not just any gasoline will work. Using unleaded gasoline is important. Diesel and E85 fuel is strongly discourage. Also, check the alcohol contents of the gas before using it. It needs to be below 10%. Make sure that you only use your the best fuel sources, as top rated weed eaters can be ruined if not.

​Mixing Your Fuel

​Mixing the fuel is easy at this point. You should have an empty 1 gallon gasoline tank on hand. Proceed to pour your oil into this can and slowly fill the rest of the can with your gasoline. Securely screw on the cap and begin to shake it to make sure everything is mixed thoroughly. Never try to mix the gas and oil inside of your weedeater. This will not work and your measurements will certainly be off and cause issues. Also, try to only mix enough fuel for 30 days. Having your mixed fuel sit for any longer than this will cause it to lose its effectiveness.

​Checking Your Work

​If for any reason you are concerned that you added the wrong ratio of fuel to your weedeater, there are a few signs that you can look out for. If you notice any smoke coming from your weedeater, it is a good indication that something is wrong with the fuel you added. In addition, if you are having trouble starting the engine itself, you may have made an error in the mixing of the oil and gas. You may also notice a change in the performance of your weedeater. 


At the end of the day, any type of oil is fine to go inside of your weedeater. You do need to make sure to only use unleaded gas, however. It is also important to get the right ratio for your type of weed eater. This information should be easily found in your weedeater's user manual. Check our other articles  Gas vs Electric string trimmer, string trimmer basics.