Modern snowblowers are made with 4-stroke engines, but if you have a cherished snowblower from years ago, you've dealt with trying to get the perfect fuel mixture for a 2-stroke engine.
Many people grew up learning to eyeball the oil-gas ratio, but properly mixing gasoline and oil will prevent your snowblower from spitting out the dark clouds of smelly smoke that nobody enjoys.
A "stroke" refers to how many stages (cylinder/crankshaft movements) a combustion engine needs to complete to finish a "power (working) stroke."
Two-stroke (two-cycle) engines require you to mix the oil with the gas in exact amounts so the oil acts as a lubricant for the crankcase.
In a 2-stroke engine, it takes one full revolution (2 stages) to complete 1 power stroke.
Four-stroke (four-cycle) engines are newer and have a separate compartment for oil, so you don't have to worry about mixing fuel. These engines are more fuel-efficient and environmentally friendly, while also giving you more torque when you need it.
It takes two revolutions (4 stages) to complete 1 power stroke inside a 4-stroke engine.
While there are benefits of using both 2-cycle and 4-cycle snowblowers, it comes down to convenience; if you're tired of mixing oil and sniffing fumes, it may be time to upgrade to a newer 4-stroke model.