The official line is that you shouldn't. But many people do, and if you are thinking of buying or selling second hand, here are some points to consider.
Infant car seats DO have expiry dates. Even if none is given on the seat itself, you should assume they will last for no more than 10 years from manufacture.
Of course that doesn't mean one moment it is safe and the next it is not. Like food with "use by" dates, car seats gradually "go off". Car seats get left in cars both day and night, where they are exposed to extremes of heat and cold, and eventually that can cause the plastic to start to break down.
Over in the US they make it very simple by printing the expiry date onto the plastic shell of the car seats (the manufacturer accepts no liability for product malfunction after this date!). Britax US gives its car seats a lifetime of 6 years and Peg Perego - the company that manufactures products for Mamas & Papas in the UK - states 5 years.
Here in the UK, things aren't quite so simple for the consumer as its not common practise to date stamp seats. Real life isn't so simple anyway. A car seat that has been stored indoors in a dry environment at moderate temperatures will last longer. But unless you know the full history of the seat I would recommend looking for nearly new items and avoid the ones that are already 5 or 6 years old.
Has it been in an accident?
A car seat is a "single use" item. Any car seat that is involved in a major crash should be binned immediately - cut off the straps, break up the shell and send it to the skip.
Sellers of used car seats tend to have children of their own (!) and realise how important it is not to put them at risk.
Did you know that you should replace your car seat seat belts after a major accident too? And yet people buy and sell second hand cars (with their seatbelts in) all the time.
But in the end it all comes down to trust, and if you're not comfortable, go out and buy a new one. If you must have a particular look, then maybe you can take the covers off the used seat, and put them onto a new seat in the same model.
Has it been cared for?
Does it have all its parts and are they all working properly?
Has it been kept clean and dry and stored indoors when not in use?
I read an auction recently where the seller had bleached/Miltoned the straps to kingdom come to try and get rid of black mildew spots! That is one car seat NOT to buy. The straps are a key part of the safety system, and the effect of harsh cleaners on the straps has not been tested, but it could weaken them. Better the mildew spots (which can be covered with strap pads) than weakened straps. Or better still buy one that has been kept clean and dry.
If you're a seller you should check these things before selling. Make sure there is no visible damage by looking under the covers to check the polystyrene shell is intact.
Buyers you need to make your own assessment of the condition. "Good condition" is very subjective, and a close up photo may tell you a lot more. When a car seat arrives check it over carefully before you think of using it.
... make sure you know how to install it properly - if you don't have the instructions, then you can pick up a copy of the instructions from the manufacturer. Both Britax and Mamas & Papas have instructions for download on their Websites.
Hope this answers any questions you may have about buying and selling second hand car seats. If you have anything to add to this Guide feel free to e-mail me.
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