Very commonly we are asked this question: when is the right time to change your engine coolant? It varies with all vehicles. It may be that you are advised to change the coolant (commonly referred to as "antifreeze") every 30,000 miles, other times there is no maintenance schedule.
Hyundai says the coolant in most of its models should be replaced around 60,000 miles the first time, after that every 30,000. The interval is every 30,000 miles on some Mercedes-Benz models with some engines, but on others it's 120,000 miles or 12 years. On still other Mercedes, it's 150,000 miles or 15 years.
Some manufacturers recommend you drain and flush the engine's cooling system and change the coolant more often on vehicles that frequent towing, which
makes your engine produce more heat. The schedule for many Chevrolet's, though, is a change at 150,000 miles regardless of how the vehicle is driven.
Many service shops, though — including some at dealerships that sell cars with "lifetime" coolant — say you should do a coolant change more often than the maintenance schedule recommends, such as every 30,000 or 50,000 miles.
Here's why: Most vehicles use long-life engine coolant (usually a 50/50 mixture of antifreeze and water) in the radiator that for several years will provide protection against boiling in hot weather and freezing in cold temperatures, with little or no maintenance. Modern vehicles typically have longer periods between fluid changes of all types.
Your vehicles coolant can deteriorate over time and should be tested to see if it's still good, as it can be hard to tell just by appearances. Even if the coolant reservoir shows sufficient coolant level and testing shows the cooling and antifreeze protection are still adequate, a coolant drain and antifreeze flush may be needed.
The coolant can become more acidic over time and lose its rust-inhibiting properties, causing corrosion. Corrosion can damage the radiator, water pump, thermostat, radiator cap, hoses and other parts of the cooling system, as well as to the vehicle heater system. And that can cause a car engine to overheat.
Thus, the coolant in any vehicle with more than about 50,000 miles should be tested periodically. That's to look for signs of rust, leaks and to make sure it has sufficient cooling and overheating protection, even if the cooling system seems to be working properly and the reservoir is full. The cooling system might also need flushing to remove contaminants no matter what the maintenance schedule calls for or how many miles are on the odometer.