What 2-Stroke Mix Ratio Does a Leaf Blower Use?

A chainsaw cuts in bursts and a trimmer is throttled up and down constantly. A leaf blower is held wide open for minutes at a time, which puts the engine at sustained peak temperature and peak piston speed. That is exactly the condition where an under-oiled mix does damage fastest.

It is why leaf blowers are unforgiving of a lean mix in a way that a lightly used trimmer is not, and why a blower is the worst tool to guess a ratio on. Get the ratio from the decal, and if you are running a backpack unit all afternoon, use a quality JASO FD oil rather than the cheapest bottle on the shelf.

Stihl, Echo, Husqvarna, Makita and RedMax blowers, handheld and backpack alike, are 50:1 across their current ranges. The engine in a backpack unit is larger and thirstier, but the ratio does not change with displacement, only the volume of fuel you go through.

Cordless and 4-stroke blowers are a separate case: if the machine has a dipstick or takes straight gas, do not add oil to the fuel at all. Some hybrid engines (Honda's 4-stroke handhelds, Stihl's 4-MIX) run on premix despite being four-stroke, so the decal remains the authority.

• A blower that loses air volume progressively over one long job, then seizes, is the classic sustained-throttle lean-mix failure.
• Excessive smoke that never clears once the engine is warm, plus oil dripping from the exhaust outlet, is too much oil in the mix.
• Backpack units that surge at full throttle often have an air filter loaded with the dust the blower itself kicks up, which is a maintenance issue rather than a mix issue. Check the filter before you touch the carburettor.