Use this calculator to determine the precise amount of 2-stroke oil needed for your gasoline, ensuring a perfect 35:1 fuel mix ratio. This ratio is common for many older 2-stroke engines, chainsaws, trimmers, and other small engine equipment.
Gallons (US)
Liters
Understanding the 35:1 Fuel Mix Ratio
A 35:1 fuel mix ratio means that for every 35 parts of gasoline, you need to add 1 part of 2-stroke engine oil. This specific ratio is crucial for the proper lubrication and cooling of 2-stroke engines. Unlike 4-stroke engines, 2-stroke engines do not have a separate oil sump; the oil is mixed directly with the fuel, lubricating the engine as it burns.
Why the Correct Ratio Matters
Engine Longevity: Too little oil can lead to insufficient lubrication, causing excessive wear, overheating, and eventual engine seizure.
Performance: Too much oil can result in excessive smoke, fouled spark plugs, carbon buildup, and reduced engine power. It can also make the engine run poorly or not start at all.
Emissions: An incorrect mix can also affect exhaust emissions, potentially leading to environmental issues and non-compliance with regulations.
Common Applications for a 35:1 Mix
While modern 2-stroke engines often use leaner ratios (e.g., 50:1), a 35:1 ratio is still common for:
Older model chainsaws
Some string trimmers and brush cutters
Certain leaf blowers
Vintage motorcycles or mopeds
Specific outboard motors
Always consult your equipment's owner's manual to confirm the exact fuel mix ratio recommended by the manufacturer. Using the wrong ratio can void warranties and damage your engine.
How to Use the Calculator
Enter Gasoline Amount: Input the total amount of gasoline you plan to use.
Select Unit: Choose whether your gasoline amount is in Gallons (US) or Liters.
Click Calculate: The calculator will instantly display the required amount of 2-stroke oil in various common units (gallons, fluid ounces, liters, milliliters) to achieve a perfect 35:1 mix.
Tips for Mixing Fuel
Use Fresh Fuel: Always use fresh, high-quality gasoline (usually unleaded, 87 octane or higher, as recommended by your manufacturer). Stale fuel can cause starting problems and engine damage.
Use Quality 2-Stroke Oil: Use a high-quality 2-stroke engine oil specifically designed for air-cooled engines (often labeled TC-W3 for marine or JASO FC/FD for land-based equipment).
Mix in a Separate Container: Never mix fuel directly in the equipment's fuel tank. Use a clean, approved fuel can.
Mix Thoroughly: After adding the oil, shake the fuel can gently to ensure the oil and gasoline are completely mixed.
Label Your Can: Clearly label your mixed fuel can with the date and the mix ratio (e.g., "35:1 Mix – 01/2024").
Store Properly: Store mixed fuel in a cool, dry place away from direct sunlight and heat. Do not store for extended periods (typically no more than 30-60 days, or use a fuel stabilizer).
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function calculateFuelMix() {
var gasolineAmountInput = document.getElementById("gasolineAmount");
var gasolineUnit = document.getElementById("gasolineUnit").value;
var resultDiv = document.getElementById("fuelMixResult");
resultDiv.innerHTML = ""; // Clear previous results
var gasolineAmount = parseFloat(gasolineAmountInput.value);
if (isNaN(gasolineAmount) || gasolineAmount <= 0) {
resultDiv.innerHTML = "Please enter a valid positive number for the amount of gasoline.";
return;
}
var oilAmountGallons; // Base calculation in gallons for consistency
// Convert input gasoline to gallons if it's in liters
if (gasolineUnit === "liters") {
// 1 US Gallon = 3.78541 Liters
var gasolineAmountGallons = gasolineAmount / 3.78541;
oilAmountGallons = gasolineAmountGallons / 35;
} else { // gasolineUnit === "gallons"
oilAmountGallons = gasolineAmount / 35;
}
// Convert oil amount to various units
var oilAmountOunces = oilAmountGallons * 128; // 1 US Gallon = 128 US Fluid Ounces
var oilAmountLiters = oilAmountGallons * 3.78541; // 1 US Gallon = 3.78541 Liters
var oilAmountMilliliters = oilAmountLiters * 1000; // 1 Liter = 1000 Milliliters
resultDiv.innerHTML =
"For " + gasolineAmount.toFixed(2) + " " + gasolineUnit + " of gasoline, you will need:" +
"" + oilAmountGallons.toFixed(3) + " Gallons (US) of 2-stroke oil" +
"" + oilAmountOunces.toFixed(2) + " Fluid Ounces (US) of 2-stroke oil" +
"" + oilAmountLiters.toFixed(3) + " Liters of 2-stroke oil" +
"" + oilAmountMilliliters.toFixed(1) + " Milliliters of 2-stroke oil";
}