Chainsaw Gas-to-Oil Ratios

Gas-to-oil Ratios

• Chainsaw manufacturers design their engines with a specific ratio of gas-to-oil set at the factory. This allows the company to test the performance of their engines. These ratios will differ with every chainsaw manufacturer, though generally the different models from the same manufacturer will all take the same gas-to-oil ratio. It's prudent to check directly with the manufacturer for your model's gas-to-oil ratio to prevent critical engine damage.
  
  

Fuel Ratio Examples

• Manufacturer's fuel ratios will vary widely from company to company, as these engines are designed differently and are intended for different uses. These ratios will range from 25-to-1 gas-to-oil, for the low end; and run up to 50-to-1 on the high end, though they will not go above this ratio. The most common fuel ratio for homeowner model chainsaws is 40-to-1, as this provides enough protection, while still allowing higher engine performance. Top-end professional models will usually take a higher blend of 50-to-1 as they need the extra gasoline to generate enough power.
  
  

Finding Your Ratio

• If the product manual can't be located and you can't contact the company directly, you'll need to find your own ratio of gas-to-oil, which can take some testing. Start on the lower end of the scale, around 30-to-1 gas-to-oil. Mix a small batch of fuel and run a several tanks of gas at this ratio. Monitor the engine acceleration and cutting performance. If the engine feels sluggish or drops power under load, slowly lean the fuel up to 40-to-1 and run a few tanks of gas at this ratio. Lean the fuel up to 50-to-1, however, if your engine wasn't designed to run at this ratio, damage may occur.
  
  

Chainsaw Fuel Information

• This type of mixed fuel can only last so long before the oil separates from the gasoline. After the oil and gas separate the oil will no longer lubricate the crankcase and piston; your engine will burn too hot and may result in damage. Also, this fuel can leave behind a gummy deposit if it gets too old and dries out. Generally, mixed fuel can only last 30 days without a stabilizer added. However, check with your manufacturer as adding a stabilizer may damage some chainsaw's carburetors.