The Importance of Air Filter Maintenance
Fall 2019

STIHL produces a variety of different types of air filters for specific engines and their applications. A dirty air filter can reduce engine performance and can make starting more difficult. It is important to know which type of air filter your STIHL tool is equipped with in order to provide the best maintenance possible. Depending on the type of material, the cleaning and maintenance of your air filter will change. Always refer to the owner’s manual for your specific model for detailed instructions regarding filter maintenance. Always replace with genuine STIHL filters and when performing filter maintenance, if possible close the choke before removing the filter.

Below is a list of current air filters used in STIHL products:

  • White Felt Element
  • Felt Element – Felt with Foam Pre-Filter
  • Fleece Element
  • Pleated Paper Element
  • Winter Style Mesh
  • PET HD2

Let us focus on STIHL’s newest type of air filter, the PET HD2 air filter. The HD2 filter has superior filtering properties when compared to our original HD filter. The filtering mesh of the HD2 filter is 15 microns vs 60 microns of the original HD filter. It does a much better job of keeping damaging abrasive dust out of the engine, leading to longer engine life. Due to the smaller mesh size, the HD2 air filter clogs faster and can clog almost completely, which can lead to a loss of power and hard starting. Due to the pleated design of this filter it can be difficult to visually tell when it is restricted. STIHL has recently changed the colour of the HD2 filter from black to white in order to facilitate filter maintenance. However, if working with materials that contain a lot of sap, it can still be difficult to tell. The best way to tell if an HD2 filter is being restricted is if the unit becomes difficult to start and/or there is a perceivable loss of power.

Now that we know more about the HD2 filter and how to determine when it requires service, we now need to know the proper procedure to clean it. STIHL has made this process virtually effortless by implementing the cleaning instructions on the filter itself, as well as the introduction of STIHL Varioclean.

STIHL Varioclean is a multipurpose cleaner that cleans the HD2 filter with ease due to its specific pH value. Just spray it on, let it soak for 10 minutes and rinse it off. Let the filter air dry, reinstall it and you are ready to work.

By Chad Dubois
National Technical Services Manager