Operating 2-stroke engines requires a precise mixture of gasoline and specialized 2-cycle oil. Unlike 4-stroke engines (like those in most cars) which have a separate oil reservoir, 2-stroke engines rely on the oil mixed directly into the fuel to lubricate the piston, crankshaft, and cylinder walls.
How to Calculate Your Mix Ratio
A ratio of 50:1 means you use 50 parts gasoline for every 1 part oil. To find the amount of oil needed, you divide the total volume of gasoline by the first number of the ratio.
For US Gallons: Total Gallons × 128 (to get fl oz) / Ratio = Fluid Ounces of Oil.
For Liters: Total Liters × 1000 (to get ml) / Ratio = Milliliters of Oil.
Common 2-Cycle Mix Examples
Ratio
Per 1 Gallon Gas
Per 5 Liters Gas
50:1
2.6 fl oz
100 ml
40:1
3.2 fl oz
125 ml
32:1
4.0 fl oz
156.3 ml
Pro Tips for Fuel Mixing
1. Freshness Matters: Gasoline begins to degrade after 30 days. Use a fuel stabilizer if you aren't using the mix immediately.
2. Mix Order: Always pour the oil into the gas can first, then add the gasoline. This helps the oil disperse more evenly.
3. Shake Well: Give the container a gentle shake before every use to ensure the oil hasn't settled at the bottom.
4. Identification: Mark your fuel cans clearly (e.g., "50:1 MIX") to avoid accidentally putting mixed fuel into 4-stroke engines or straight gas into 2-stroke tools.
function toggleCustomRatio() {
var ratioSelect = document.getElementById("mixRatio");
var customContainer = document.getElementById("customRatioContainer");
if (ratioSelect.value === "custom") {
customContainer.style.display = "block";
} else {
customContainer.style.display = "none";
}
}
function calculateTwoCycleMix() {
var gasAmount = parseFloat(document.getElementById("gasAmount").value);
var gasUnit = document.getElementById("gasUnit").value;
var ratioSelect = document.getElementById("mixRatio").value;
var ratio;
if (ratioSelect === "custom") {
ratio = parseFloat(document.getElementById("customRatioValue").value);
} else {
ratio = parseFloat(ratioSelect);
}
var resultDiv = document.getElementById("mixResult");
var oilOutput = document.getElementById("oilOutput");
var summaryText = document.getElementById("mixSummary");
if (isNaN(gasAmount) || gasAmount <= 0) {
alert("Please enter a valid amount of gasoline.");
return;
}
if (isNaN(ratio) || ratio <= 0) {
alert("Please enter or select a valid mix ratio.");
return;
}
var oilAmount;
var unitLabel;
if (gasUnit === "gallons") {
// 1 Gallon = 128 fl oz
oilAmount = (gasAmount * 128) / ratio;
unitLabel = " Fluid Ounces (fl oz)";
} else {
// 1 Liter = 1000 ml
oilAmount = (gasAmount * 1000) / ratio;
unitLabel = " Milliliters (ml)";
}
oilOutput.innerHTML = oilAmount.toFixed(2) + unitLabel;
summaryText.innerHTML = "To achieve a " + ratio + ":1 mix with " + gasAmount + " " + gasUnit + " of gasoline.";
resultDiv.style.display = "block";
// Smooth scroll to result
resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}