How Much 2-Stroke Oil for 6 Gallons of Gas?
At 50:1, add 15.4 fl oz (454 mL) of 2-stroke oil.
At 40:1, add 19.2 fl oz (568 mL).
At 32:1, add 24 fl oz (710 mL).
Not sure which ratio? Use the one in your owner's manual or on the fuel cap. Most modern handheld equipment is 50:1. Other amounts: open the calculator.
Six gallons is the classic portable outboard tank size, so this is the batch most small-boat owners mix. Check the decal on the motor or tank: outboards with oil injection must not get premix.
Oil for 6 Gallons at Every Ratio
| Ratio | Oil (fl oz) | Oil (mL) | Easy measure | Typically used for |
|---|---|---|---|---|
| 50:1 | 15.4 fl oz | 454 mL | about 1.9 cups | Modern chainsaws, trimmers, blowers; most modern outboards |
| 40:1 | 19.2 fl oz | 568 mL | about 2.4 cups | Older equipment, some trimmers and outboards, many dirt bikes |
| 32:1 | 24 fl oz | 710 mL | about 3 cups | Dirt bikes and motocross, high-load engines |
| 30:1 | 25.6 fl oz | 757 mL | about 3.2 cups | Vintage outboards |
| 25:1 | 30.7 fl oz | 908 mL | about 3.8 cups | Older equipment, break-in when specified |
| 20:1 | 38.4 fl oz | 1136 mL | about 4.8 cups | Vintage engines, some racing |
| 16:1 | 48 fl oz | 1420 mL | about 6 cups | Antique engines and outboards |
6 gallons is 22.71 liters. These amounts are for US gallons. If your manual uses UK (imperial) gallons, which are about 20% larger, 6 imperial gallons at 50:1 needs 546 mL of oil.
How Precise Do You Need to Be?
Staying within about 10% of the target amount keeps you close to the intended ratio. For 6 gallons at 50:1 that means 13.8–16.9 fl oz of oil, and at 40:1, 17.3–21.1 fl oz.
At this batch size, an extra 1 fl oz of oil turns a 50:1 mix into about 46.9:1, and 1 fl oz too little makes it about 53.5:1. Running slightly rich (more oil) is safer for the engine than running lean.
Mixed 6 Gallons at the Wrong Ratio?
You don't need to throw it out. To correct a full 6-gallon batch:
| Situation | Fix |
|---|---|
| Mixed 40:1, need 50:1 | Add 1.5 gallons of fresh gas (7.5 gallons total) |
| Mixed 50:1, need 40:1 | Add 3.8 fl oz more oil |
| Mixed 50:1, need 32:1 | Add 8.6 fl oz more oil |
| Mixed 32:1, need 50:1 | Add 3.38 gallons of fresh gas (9.38 gallons total) |
Adding gas makes the batch bigger, so only lean out a mix if you will use the extra fuel within about a month.
How to Mix 6 Gallons
- Measure the oil, for example 15.4 fl oz (454 mL) for 50:1. A ratio measuring cup reads directly in ounces and mL.
- Add the oil to the tank first, then fill with 6 gallons of gas at the pump so the flow mixes it.
- Cap it tightly and shake for about 30 seconds. A fuel can with a sealing cap prevents spills while you shake.
- Write the ratio and date on the can. Shake again before each refill if the can has been sitting.
6 Gallons: Common Questions
How much oil for 6 gallons of gas at 50:1?
6 gallons at 50:1 needs 15.4 fl oz (454 mL) of 2-stroke oil.
How much oil for 6 gallons of gas at 40:1?
6 gallons at 40:1 needs 19.2 fl oz (568 mL) of 2-stroke oil.
How much oil for 6 gallons of gas at 32:1?
6 gallons at 32:1 needs 24 fl oz (710 mL) of 2-stroke oil.
I mixed 6 gallons at 40:1 but my engine needs 50:1. What do I do?
Add 1.5 gallons of fresh gas (7.5 gallons total). That brings the batch back to 50:1 without wasting it.
How long does 6 gallons of mixed fuel last?
Mixed 2-stroke fuel without stabilizer is best used within about 30 days. A fuel stabilizer extends that; follow the storage time on the stabilizer's label.
Other Fuel Amounts
Need a ratio guide instead? See 50:1, 40:1, 32:1 or all ratios.