Vintage Chainsaw Mix Ratios: McCulloch, Homelite, Poulan and More
Most chainsaws from the 1950s and 1960s run 16:1. Most from the 1970s and 1980s run 32:1 to 40:1 with the maker's own oil. Saws from the 1990s onward generally run 50:1.
Old manuals often list two ratios: a rich one for "regular" oil and a leaner one for the brand's own oil. With a modern JASO FD synthetic, use the leaner number, and don't go past it.
Old chainsaw mix ratio chart
Typical original recommendations by brand and era. Models differ, so confirm with the manual, the fuel cap or a collector forum for your model.
| Brand | Era | Usual ratio | Calculator |
|---|---|---|---|
| McCulloch | 1950s to mid-1960s | 16:1 to 20:1 | Mix at 16:1 |
| McCulloch | late 1960s to 1980s | 40:1 with McCulloch oil (older manuals 20:1 with other oils) | Mix at 40:1 |
| Homelite (XL-12, Super XL, etc.) | 1960s to 1980s | 16:1 with standard oil, 32:1 with Homelite 2-cycle oil | Mix at 32:1 |
| Poulan | 1970s to 1990s | 16:1 early; 32:1 to 40:1 with Poulan oil later | Mix at 32:1 |
| Stihl (041, 031, 08S, etc.) | 1960s to 1980s | 25:1 with standard oil, 40:1 with Stihl oil | Mix at 40:1 |
| Stihl | 1990s onward | 50:1 | Mix at 50:1 |
| Husqvarna | 1970s to 1980s | 50:1 with Husqvarna oil; 25:1 to 33:1 with other oils | Mix at 33:1 |
| Echo | before about 2000 | 32:1 (many later approved for 50:1 with Echo oil) | Mix at 32:1 |
| Pioneer, Jonsered, Partner | 1970s to 1990s | 25:1 to 40:1 depending on model and oil | Mix at 32:1 |
| Very early saws (Mall, Disston, Clinton, etc.) | 1940s to 1950s | 16:1 or richer | Mix at 16:1 |
How much oil for vintage chainsaw ratios
| Ratio | Per US gallon | Per 6 gallons | Per litre |
|---|---|---|---|
| 10:1 | 12.8 fl oz | 76.8 fl oz | 100 mL |
| 16:1 | 8 fl oz | 48.0 fl oz | 62.5 mL |
| 20:1 | 6.4 fl oz | 38.4 fl oz | 50 mL |
| 24:1 | 5.3 fl oz | 32.0 fl oz | 41.7 mL |
| 25:1 | 5.1 fl oz | 30.7 fl oz | 40 mL |
| 32:1 | 4 fl oz | 24.0 fl oz | 31.3 mL |
| 40:1 | 3.2 fl oz | 19.2 fl oz | 25 mL |
| 50:1 | 2.6 fl oz | 15.4 fl oz | 20 mL |
Most chainsaw users mix 1 gallon or 5 litres at a time. See how much oil for 1 gallon or 5 litres, or use the chainsaw calculator.
Why old chainsaws used 16:1, and can you run 50:1?
Early saws were designed for the non-detergent motor oils of the day, which needed a lot of oil to protect plain bearings and big, heavy pistons. As dedicated 2-stroke oils improved in the 1960s and 1970s, makers printed leaner ratios for their own oil.
- Saws with two ratios in the manual (for example Homelite's 16:1 regular / 32:1 Homelite oil): with a modern JASO FD oil, use the leaner of the two.
- Saws rated only 16:1 (1950s and early 1960s): many collectors run them at 20:1 to 25:1 with modern synthetic and report good results, but going all the way to 50:1 removes most of the margin on bearings that may already be worn.
- Saws rated 32:1 or 40:1: run the rated ratio. Some makers (Echo, for one) later approved 50:1 for older models with their own oil; check before you switch.
- Too rich is a smaller problem than too lean. Extra oil causes smoke, a wet muffler and plug fouling. Too little causes a scored piston. See lean mixture symptoms.
Changing the ratio changes the tune. A different ratio slightly changes how much fuel the carb delivers. After any change, check the high-speed screw: the saw should four-stroke a little with no load and clean up in the cut.
Reviving an old chainsaw
- Empty and clean the tank. Old fuel turns to varnish. Replace the in-tank filter and fuel line, which are almost certainly hard and cracked.
- Clean or rebuild the carburetor. Diaphragms in old Walbro and Tillotson carbs stiffen with age; rebuild kits are cheap. Carb cleaner helps with varnish.
- Test compression. Most healthy small saws read well over 100 psi; many collectors look for 120 psi or more.
- Fit a new spark plug and read it after the first run. See how to read a spark plug.
- Check the chain oiler and fill with bar oil. Never use the bar oil reservoir for premix.
- Use fresh, preferably ethanol-free, fuel. Ethanol attacks the rubber and some plastics in older saws. See alkylate fuel and eco oils.
Frequently Asked Questions
What is the mix ratio for an old McCulloch chainsaw?
McCulloch saws from the 1950s to mid-1960s usually call for 16:1 to 20:1. Later models from the late 1960s to the 1980s were commonly rated 40:1 with McCulloch oil. Check the manual or fuel cap for your model.
What is the mix ratio for a Homelite XL-12 or Super XL?
Homelite manuals for these saws commonly list 16:1 with standard 2-cycle oil and 32:1 with Homelite oil. With a modern JASO FD synthetic oil, 32:1 is the usual choice.
Can I run an old 16:1 chainsaw at 50:1?
It is not recommended. Modern oil is much better, but old bearings are worn and the engine was designed for a rich mix. Many collectors run 16:1 saws at 20:1 to 25:1 with modern synthetic oil.
How much oil do I mix for 16:1?
At 16:1 mix 8 fluid ounces of oil per US gallon of gas, or 62.5 mL per litre.
What oil should I use in a vintage chainsaw?
Use a quality air-cooled 2-stroke oil rated JASO FD or ISO-L-EGD at the ratio for your saw. Don't use automotive motor oil or outboard TC-W3 oil in an air-cooled chainsaw.