Husqvarna PT-26D Operator's Manual page 54

Presentation
IMPORTANT INFORMATION:
Never fill a hot engine with cold coolant. Risk of
extensive engine damage.
Only fill antifreeze and water ready mixed in a 50/50 ratio.
Check the level when the engine has been driven for a few minutes after filling. There could have been air in the
system which has now been released.
Antifreeze
Only use a glycol based antifreeze that is approved by the applicable norms BS 6580:1992 or ASTMD 3306-89 or
AS 2108-1977 (indicated on the packaging).
The antifreeze agent must be intended for use with light alloy engines.
Your Husqvarna supplier can provide the correct type of antifreeze agent.
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