The 25:1 ratio is an oil-rich mix for vintage and heavy-duty 2-stroke engines. Common in older European equipment and some marine outboards. Mix 5.12 fl oz per gallon.
Quick Reference
Gallons
Liters
Fuel (Gallons)
Oil (fl oz)
1 gallon
5.12 fl oz
2 gallons
10.24 fl oz
2.5 gallons
12.8 fl oz
3 gallons
15.36 fl oz
5 gallons
25.6 fl oz
10 gallons
51.2 fl oz
Also see
50:1
40:1
32:1
24:1
20:1
16:1
100:1
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Facts About 25:1
⛽
PER GALLON
5.12 fl oz
🧪
PER LITER
40 mL
📐
OIL PERCENTAGE
3.8%
Equipment Rated for 25:1
This equipment uses a 25:1 mix ratio. Always check your owner's manual to confirm.
Older Husqvarna
Jonsered
Partner
Vintage McCulloch
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⚠️
Ethanol Hazard
Use E0 when available, or E10 if your manual allows it. Higher-ethanol blends absorb water faster, age poorly, and can damage small-engine fuel systems.
Ready to Mix?
Use the calculator to get exact fuel and oil amounts.