How it Works - Four-Stroke Premix Oil and Fuel Engines

Four-stroke premix oil and fuel engines combine the best of two-stroke and four-stroke engine technologies. They offer excellent acceleration and torque, are easy to operate and release fewer emissions than typical two-stroke designs, making them ideal for power tools and outdoor power equipment.

WATCH: See the benefits of four-stroke premix engines.

How does a four-stroke premix and fuel engine work?

Four-stroke premix engines combine a four-cycle engine design with the lubrication elements of a two-stroke.  

As the name implies, four-stroke premix engines go through a four-stroke combustion process (intake, compression, power and exhaust) to produce energy but are lubricated by an oil and fuel mixture instead of oil alone.  

Benefits of the design:

  • High-fuel efficiency and fewer emissions 
  • Easy maintenance with the use of the standard fuel-oil premix 
  • Improved lightweight, compact construction 
  • Ability to operate at various angles 
  • Excellent acceleration, delivering impressive lugging power and higher torque 
  • No extreme sound levels, even at the highest power 

Lubrication considerations

While four-stroke premix engines provide unique benefits, they also bring unique lubrication challenges.
Specifically, ash control is critical as the oil and fuel mixture passes through the engine valves. Too much ash can lead to deposit formation that can cause poor performance, excess heat that can damage engine components, or worse, engine failure.