Probably not, unless the car seat is nearly new, the instructions are intact and you are certain it has never been in an accident or subject to a recall. "Used products increase the chance that something's broken, worn out or doesn't work right," says Sandy Jones, co-author with her daughter, Marcie Jones, of Great Expectations: Your All-in-One Resource for Pregnancy & Childbirth, and Great Expectations: Baby's First Year (Sterling Publishing).
Ideally, any gear you rely on to protect your child-whether it's car seats, strollers, even cribs-should be purchased new.
Safety standards change, and straps, buckles and harnesses wear out. "With cribs, screw holes can weaken, and the glue and staples that hold the bars could be affected," Jones says. If you do buy a used crib, inspect it carefully to make sure all the parts are present and in working order, and use a soda can to test the spacing of the bars; if the can fits through, the bars are too far apart and pose a hazard.
Avoid strollers sold at yard sales, as their treads tend to be worn out and the reclining mechanisms may not work well; if you accept a used stroller from a trustworthy friend or relative, first roll it around with a child inside. "Wheels get out of alignment, veer to one side or become wobbly," says Jones. "You can't tell how it will steer until there's a weight inside."
In general, don't accept used products related to hygiene or feeding, like a crib mattress or breast pump.
(Rental pumps are the exception; the bottles and tubing are designed so that the milk never touches the working parts of the pump.)