HL 91 K
English
27
Maintenance Requirements
The maintenance instructions in this 
manual are based on the application of 
the recommended 2-stroke fuel-oil 
mixture (see also instruction "Fuel"). 
Deviations from this recommendation 
regarding quality and mixing ratio of fuel 
and oil may require shorter maintenance 
intervals.
Limitations
This Emission Control Systems 
Warranty shall not cover any of the 
following:
1. repair or replacement required 
because of misuse, neglect or lack 
of required maintenance
2. repairs improperly performed or 
replacements not conforming to 
STIHL Limited specifications that 
adversely affect performance 
and/or durability, and alterations or 
modifications not recommended or 
approved in writing by STIHL 
Limited
3. replacement of parts and other 
services and adjustments 
necessary for required maintenance 
at and after the first scheduled 
replacement point