Why do lawn mowers run on only gasoline, while snow blowers, leaf blowers, trimmers and edgers require a mix of gasoline and oil? I've always wondered this, but never thought to ask. Thanks, Donna

Hi Donna,

The main reason is horsepower per pound of engine weight. Lawn mowers and other devices that “Carry” their own weigh have “4 cycles” motors. These run on straight gas. Have a crankcase to hold lubricating oil. Produce power only on the forth cycle. 1- Exhaust, 2- intake fuel/air, 3- compression and 4- power where the fuel/air mixture is burnt.

Lawn edger and trimmers and other devices use a 2 cycle engine. They are lighter to carry. They have no crank case for oil. Oil for lubrication is mixed with the fuel. As the fuel enters the hot engine, the fuel evaporates leaving some of the oil behind to lube the engine. You may notice that 2 cycle motor smoke more the 4 cycle. This is the oil burning off. These engine produce power every cycle. 1- Power/exhaust, 2- Intake/compression.

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