should i change my coolant
 

yesterday i checked my coolant and it is resistant to frezzeing temp.(-40c)
the car is impreza sti 2003 and did not change the coolant before
should i change it before winter or since it is still resistant to freezing temp.
should i let it as it is
thanks
pit

if it's still being serviced properly, coolant should be fine.

Service schedule says it should be renewed at 3yr/30,000 mile service. It may stop freezing OK but there are corrosion inhibitors which do deteriorate with age. Just had mine changed.

Cheers Diccy.