For some vehicles, you're advised to change the coolant every 30,000 miles. For others, changing the coolant isn't even on the maintenance schedule.
For example, Hyundai says the coolant (what many refer to as "antifreeze") in most of its models should be replaced after the first 60,000 miles, then every 30,000 miles after that. The interval is every 30,000 miles on some Mercedes-Benz models, 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 changing the coolant more often on vehicles subjected to "severe service," such as frequent towing. The schedule for many Chevrolets, though, is to change it 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 it 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) that for several years will provide protection against boiling in hot weather and freezing in cold weather, with little or no maintenance. Modern vehicles also have longer intervals between fluid changes of all types partly because environmental regulators have pressured automakers to reduce the amount of waste fluids that have to be disposed of or recycled.