Q. Should I be wary of buying a secondhand car seat for my child?

A. There are several reasons we at CR don't recommend that consumers buy used car seats, and responsible parents should be aware of them: As a buyer, you usually can't be 100 percent sure of a secondhand car seat's history, including whether it has been involved in a crash, its expiration date as set by the manufacturer, and its recall status.

It's most crucial to know whether a secondhand car seat has ever been involved in a crash. Even if the seat looks undamaged, crash forces could have stressed the components in ways that aren't visible, thereby reducing its ability to protect a child in the future. As a buyer, you’d have to rely just on the seller's word to know.

Expiration dates are also key: Obeying them helps ensure that the car seat components are still strong and that the seat has the latest safety features. So any would-be buyer would need the labels and owner's manual to know how much longer a secondhand car seat could be used.

Also, a buyer would need to research whether there have been recalls, though that fact alone is not always a deal breaker. "If you find that a recall has been issued, contact the manufacturer, "says Jennifer Stockburger, who leads the child seat team at our auto test track. "Some fixes can be easily remedied."

Given the high bar for assessing a secondhand car seat, unless you can get one from someone you know and trust—who can help you determine that it really checks out—it's generally best to buy a new one.

Down the road, when you're ready to dispose of it, make sure your used car seat doesn't tempt anyone dumpster diving: Carefully remove all fabrics, harnesses, and buckles. Then mark the remaining shell "Do Not Use" and check with your local authorities to see whether any components can be recycled.

For related information, check our car seat buying guide