Time: 1-2 hrs

Difficulty: moderate-diffucult (hose access/proper tools)

Cost: $100-150

WHY

The coolant's job is to cool the engine without eating the parts it's meant to protect. Additives inhibit corrosion, enhance lubricity, extend the temperature range, etc. When these additives break down or become polluted, parts wear quickly, gaskets leak, and overheating occurs; which is costly!

Radiator hoses degrade from the inside out, making pending failure difficult to detect. Cracks and pinhole leaks can lead to loss of coolant or rupture. Fresh hoses can prevent a steaming roadside breakdown.

WHEN

Most extended life coolants are meant to last up to 5 yrs/150,000 miles. If the coolant looks dark, rusty, or leaves a film on the overflow reservoir, it's overdue. The thermal-protection range can also be tested. Staying ahead on the maintenance schedule provides peace of mind against costly water pump and head gasket failures.

With hoses, the replacement range is anywhere from 2-8 years. It makes sense to replace them with the coolant every 5 years/150,000 miles. If they look cracked/dried-out or feel overly soft or thin when squishing them by and, replace them sooner.

METHOD

When the vehicle is cooled down, drain the coolant and replace the hoses. While you're at it, consider replacing the thermostat. Add coolant to the radiator and overflow reservoir. Run the vehicle until it reaches normal operating temperature. This will ensure the thermostat opens up and circulates the fluid throughout the engine. Turn off the engine  and wait for the vehicle to cool completely (like overnight), then fill the radiator completely and the reservoir to range.

Fluid and Hoses - https://youtu.be/XT9MhO-3yak

Complete Coolant Exchange/Flush - https://youtu.be/-D-I5rEkcK0

The video below shows the process on a 2006-2013 era Toyota RAV4.