Grass trimmer maintenance

For long-term top performance, your brushcutter or grass trimmer needs regular maintenance. Find out the key points along with troubleshooting tips.

A STIHL FS 240 brushcutter lies on the ground in a yard, with play equipment and a person approaching in the background

Before you start: important points about grass trimmer maintenance 

A man wearing gloves cleans the cutting tool of a STIHL FS 131 brushcutter.

Grass trimmers use a rotating mowing line to quickly cut long grass and get it under control; brushcutters function similarly, and may use blades to tackle the toughest undergrowth. The maintenance steps required are the same in both cases, and the first step is always to read carefully through the operating instructions. you will find information about the most important maintenance tasks there.

Only perform maintenance tasks as advised and described in your operating
instructions. For all other repairs and servicing visit your STIHL dealer, who has the expertise to safely restore your tool to working condition. 
An open canister of STIHL MotoMix fuel standing on grass, with a hand in the foreground unscrewing the fuel cap on a grass trimmer.

Choosing the right fuel for your petrol grass trimmer

It’s essential to use the right fuel for your petrol grass trimmer or brushcutter - we recommend STIHL MotoMix. Not only is it perfectly formulated for the engine and ready- mixed, it also offers very low emissions, high performance, and is storable for long periods. The special STIHL filling system prevents fuel spillage and overfilling of the tank.

Checking the cutting tool

Your grass trimmer works with mowing heads that can be quickly and easily replaced as required. The condition of the cutting tool is all-important to the smooth operation of your grass trimmer, so you should regularly check it as part of your grass trimmer maintenance routine. It is crucial to note that the various types of mowing heads have different requirements:

  1. For a mowing head with line (e.g. AutoCut, SuperCut): open the mowing head and check that the line is wound correctly – the lines should not cross over each other. If they are not correctly aligned, wind a new genuine STIHL mowing line onto the head.
  2. Mowing head with plastic blades (PolyCut): inspect the mowing head for cracks – these signs of wear let you know when the tool needs to be replaced. All three blades of the PolyCut must always be replaced as a complete set.
  3. Metal cutting tools (e.g. a grass-cutting blade or shredder blade) must be checked in case they need sharpening. If they are bent or broken, they must be replaced.

Maintenance checklist

After completing your maintenance work, clean the grass trimmer guard and cutting tool with a damp cloth or a soft brush; for very stubborn dirt you can use an all-purpose cleaner. As you clean, check that the components are mounted securely and correctly.

A man refuels a STIHL brushcutter with a mixture of gasoline and oil.

Why won’t my brushcutter or grass trimmer start?

This may be because of the petrol mixture – you should not be using fuel that is over 30 days old. If you’re not sure how long the fuel has been in the tank of your grass trimmer, it’s best to replace it.

Summary: grass trimmer maintenance

  • For safe maintenance, always read the operating instructions first.
  • Make sure you use the right petrol mixture in your grass trimmer.
  • Always check the grass trimmer cutting tool before you start work.
  • Always clean the grass trimmer after finishing work.
  • Replace the fuel mixture as required.