Change your coolant on schedule
Coolant doesn't last forever. You have to change it every 24,000 miles (green coolant) or 100,000 miles (extended-life coolant). If you keep driving on worn coolant, expect to replace the radiator, heater core and water pump.
Change your fluids regularly
Cabin air filter
Test your coolant
Use a voltmeter to test coolant
Test your coolant with a voltmeter. Set your digital voltmeter on the lowest DC setting reading and dip the positive probe right into the coolant. Touch the negative probe to the negative battery terminal and rev the engine to 2,000 rpm. If the reading is .4 volts or more, your coolant is toast.
Clean your headlights
Clean corroded battery terminals
Defroster grid out of action
Don't mix different types of coolants
An easy avoidable “oops”
Green, yellow, red, orange and blue coolants create cool “mud” when mixed. Cost of a new heater core: $400 to $1,000.