Many people don’t know, unless they read their winch manual carefully.
Most manuals says you should NEVER run the line out using the winch motor. Instead you should always put is in free spool and pull the line out manually. That is the case for most brands of winches, including the Warn Brand.
The reason is that, on most winch brands, including Warn winches, there is a friction brake inside the drum.and it is always on when you are running the line out using the winch motor. This is to prevent a “Run Away” while un-spooling under a load. The motor is actually overcoming the brake when running the line out and thus the drum gets very hot from the friction. . (Some other brands have a braking system outside the drum.)
One enemy of synthetic winch line is heat..
In Suzanne’s case the melted winch line didn’t cause the line to break. I suspect it was one of the other enemies of synthetic winch line, Old Age and Sunlight..
Synthetic line is great and nicer to use than steel cable but it can be damaged by heat, and sunlight as well as sharp rocks. Since mot people go a long time between use of their winch, one should inspect your winch line from time to time.
Whether you have Synthetic winch line or Steel Cable, you should not use the winch motor to un-spool your winch line. Doing so can wear out the winch braking system if you have a winch with a braking system in the drum.