Ratio Rite Cups, Mixing Bottles and Gas Cans for 2-Stroke
Published September 20, 2026 · 7 min read
Getting the ratio right is arithmetic, and a calculator settles it in two seconds. Getting the same mix twice is a hardware problem, and that is what the pit-box kit exists to solve. The gap between “50:1” and a can of fuel that is actually 50:1 is a measuring vessel you can read, a can you can pour from without losing half an ounce down the side, and a label that tells you in October what you mixed in June.
The tool that removes the arithmetic: a ratio cup
The Ratio Rite is the one everybody in a motocross pit already owns. It is a moulded cup with a column printed for each common ratio, so you find your ratio’s column, read across from the gallons you are mixing, and fill the oil to that line. No conversion, no calculator, no doing mental division with cold hands.
Two things make it more useful than it looks. It also carries plain fluid-ounce and millilitre scales, so it doubles as an ordinary graduated cup for gearbox oil or coolant. And because the ratio columns are moulded in rather than printed on, they survive being left in a fuel-soaked toolbox for a decade.
The limitation is that the columns cover the ratios that existed when the cup was designed, which is the 16:1 through 50:1 band. Run something outside that, like the 100:1 some synthetic oils allow, and you are back to reading the plain scale.
Graduated mixing bottles
A mixing bottle is a graduated container with a screw cap, marked in both fluid ounces and millilitres. You pour the oil to the line, add a little fuel, cap it, shake it, and pour that concentrate into the can. It is the neatest way to handle small batches, and the only sensible way to handle a ratio a ratio cup does not print.
Look for three things: graduations every 0.1 fl oz or 5 ml rather than in half-ounce steps, a narrow neck so the meniscus sits in a readable part of the scale, and a cap that actually seals, because an unsealed bottle in a truck is a smell you live with for months.
A kitchen measuring cup is the common substitute and it is usually too coarse. A 50:1 mix wants 2.56 fl oz per gallon, and a kitchen cup graduated in quarter-cup steps is asking you to split a 2 oz gap by eye. Guessing high costs you a fouled plug. Guessing low costs a piston. If you do use one, retire it from food use permanently.
A digital kitchen scale is the accurate outlier. Two-stroke oil runs about 0.87 g/ml, so the 2.56 fl oz for a gallon at 50:1 is roughly 66 g. It is precise and repeatable, and it is also slower than reading a line, which is why almost nobody does it twice.
Single-use oil bottles, and when the maths stops working
The little 2.6 oz bottles that Stihl, Husqvarna and Echo sell at the counter are genuinely convenient: one bottle, one gallon, nothing to measure. That convenience is built on an assumption, which is that you are mixing 50:1. The sums line up because 2.6 oz times 50 is 130 oz against 128 in a gallon, so there is a sliver of margin. The 6.4 oz bottles work the same way for 2.5 gallons.
Step off 50:1 and the convenience evaporates. At 40:1 a 2.6 oz bottle only treats about 0.8 of a gallon, so a bottle per gallon leaves you lean in a machine that wanted more oil, not less. At 32:1 it is worse. If your equipment is older than the mid-1990s, check the decal before you assume the bottle matches the can.
They also cost several times what the same oil costs in a quart, so they earn their place as a truck-box backup rather than as the way you mix every week.
Gas cans: size first, spout second
Size is the decision that matters, because mixed fuel has a shelf life and a half-empty can is just slow waste. E10 pump fuel starts losing its lighter fractions within weeks, and once mixed it does not improve. Buy the smallest can that covers a normal session:
| Job | Can size | Oil at 50:1 | Oil at 40:1 |
|---|---|---|---|
| Trimmer, blower, hedge trimmer | 1 US gal | 2.56 fl oz | 3.2 fl oz |
| A saw, an afternoon of firewood | 2 US gal | 5.12 fl oz | 6.4 fl oz |
| Dirt bike at the track, a full work day | 2.5 US gal | 6.4 fl oz | 8 fl oz |
| A crew, or a weekend on the water | 5 US gal | 12.8 fl oz | 16 fl oz |
Spout second. Every portable fuel container sold in the US since 2009 has to be self-closing with a single opening and no separate vent, which is why modern cans glug and spill in a way the old vented ones did not. The cans worth paying for are the ones that solved that: a thumb-button or lever spout that opens the flow deliberately, and a nozzle narrow enough to reach a trimmer’s tank without a funnel.
A few habits that cost nothing:
- Red is gasoline. Yellow is diesel, blue is kerosene. Keep the convention even if the can is only ever yours.
- Fill on the ground, never in a truck bed or on a plastic liner, so static has somewhere to go.
- Label every can with the ratio and the mix date, on tape you can peel off and rewrite.
- Keep a can per ratio if you run more than one. Mixing them up is the single most common way a machine gets the wrong fuel.
- Store in the shade. A can baking on a trailer vents, and what it vents is the part of the gasoline that makes it start easily.
The one filter worth having
A water-separating filter funnel sits between the can and the tank and stops both water and debris. The mesh passes fuel and holds water back, so anything that has condensed in a can over a cold night stays in the funnel where you can see it.
It matters most for anything stored outdoors or run seasonally, and most of all for marine fuel, where a vented tank in humid air absorbs enough water to phase separate. The outboard fuel mix guide covers what that failure looks like and why it strips the oil out of your mix along with the octane.
What you can skip
- A funnel for a can with a decent spout. If you need a funnel to fill a trimmer, the spout is the problem.
- Fuel testers and octane gauges. Interesting, not actionable. Fresh fuel from a busy station solves the same problem.
- Anything sold as a “mixing additive”. The oil is the additive. A stabiliser is worth having for fuel that will sit; nothing else in that aisle is.
- A five gallon can for a household with one trimmer. You will throw away more fuel than you burn.
Putting it together
The whole routine is four steps once the kit is on the shelf: measure the oil into the empty can, add the fuel so the pour does the stirring, cap and shake, then label it. The full procedure, including the fuel-quality part that no measuring cup can fix, is in how to mix 2-stroke fuel.
Work out the exact amount for whatever can you have in front of you:
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For printable tables see the 50:1, 40:1 and 32:1 pages, the full mix charts, or the 2-stroke mix chart guide for every ratio in one place. Machine-specific ratios are on the chainsaw, string trimmer and dirt bike pages, and if you are still choosing a bottle, the best 2-stroke oil guide sorts them by rating and use case.
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