My feed

to access all these features

Confused about car seat regulations? Find baby car seat advice here.

Car seats

Do you really need to replace car seats after 5 years?

51 replies

Lozzer · 31/08/2009 13:08

Just wondering. I have a car seat I bought for DS1 back in 2001. Both he and his brother used it and then it has been sitting in a cupboard for several years. Now DD1 is getting to 9 months and I was thinking to dust down the old seat and have DD1 use it.
I emailed Maxi Cosi about replacement car seat covers and they recommend replacing the whole car seat after five years. Something about plastic becoming brittle. Does anyone with a technical background know if this is true? The seat appears to be in good condition and it was never in a car that crashed.
Many thanks, Lorien

OP posts:
FabBakerGirlIsBack · 01/09/2009 10:40

We have the maxi cosi rodi. Does anyone know how long these are safe for? It is a booster with a back.

clop · 01/09/2009 10:42

I think it must depend on likely wear and tear. We rarely use the car so I don't worry about using a 6yo seat for DC4. If the seat had been used daily for 5 years, that would be a far different story.

thinkaboutthepepilepticdogs · 01/09/2009 10:49

Clop - Its not about how often it has been used or not used. Its about the degrading of the polymer chains in the plastic over time. This can be made worse if the seat has been exposed to extremes of heat or cold. Eg, in a car for many years exposed to the cold of the winters, in the loft for storage exposed to the heat of an attic in the summer and the cold of the winter.

The type of damage that you ought to be worried about is the type that you can't see. You can't look at a plastic an say 'no, its ok it hasn't become brittle over time'.

If you are happy to take the risk with your child in an old seat then do, but don't put your child in them because you think it hasn't been used much so it must be fine, or you've had a look and you think its in good condition.

Schrodinger · 01/09/2009 10:52


Unless it it a booster, designed for older children, then you need to replace it. The plastic WILL degrade after this time, meaning the integrity of the seat is compromised.

Why even risk it?

CyradisTheSeer · 01/09/2009 10:53

This reply has been deleted

Message withdrawn

thinkaboutthepepilepticdogs · 01/09/2009 10:58

A good webpage detailing polymer (plastic) degradation can be found here. Its language isn't too technical and gives a good overview.

SparklyGothKat · 01/09/2009 11:02

confused now lol.. so should I replace the kids' highbacked boosters?

FabBakerGirlIsBack · 01/09/2009 11:22

Thank you Cyradis.

We are under 6 years but only by about half a year so will get a new seat.

CyradisTheSeer · 01/09/2009 11:27

This reply has been deleted

Message withdrawn

clop · 01/09/2009 13:39

Our 6yo seat has mostly lived in a mild-temp corner of the living room. But I will look for its expiry date. Ta.

SparklyGothKat · 01/09/2009 15:48

just spoke to my sister who brought her carseats at the same time and my seats were brought in 2005, so we have another 1-2 years

clop · 01/09/2009 17:00

There have been several previous threads on MN about this!

This one saying do we really have to be that wasteful?, and another thread expressing doubts about it all.

I still don't know what to do, it's the waste rather than the money that bothers me. Maybe I'll bring our carseats inside on cold days .

That GMTV video linked to previously is so blurry (the resolution is equally poor in YouTube version) that I can't figure out what it actually shows. Straps breaking? Some plastic central bit of the seat somehow slicing the dummy in half? I can't see what it is.

Schrodinger · 01/09/2009 17:20

it's not just heat that perishes the plastic, it's atmosphere, quick changes in temp, overall though, it's just age.

It's to do with the plastic fracturing when it gets old. If this happens in a critical area of the seat (main structure, or a part holding the straps) then the seat won't be safe.

Feierabend · 01/09/2009 17:41

Oh I don't know, I used to work for a research lab that develops plastics / materials and components for car manufacturers. I am not saying the advice is wrong, but surely technology is advanced enough to come up with materials that can withstand more than 5 years use? I mean, we don't have to replace our cars every 5 years either. And yes, what about seats that are designed for older children from 4-12?

thinkaboutthepepilepticdogs · 01/09/2009 17:46

Clop - As schrodinger says, its many factors that affect the condition of the plastic. Even light will cause degradation over time.

Polymer degradation isn't a ploy to get people to buy more car seats, it affects any plastic, not just car seats.

If you think its better to not waste money then that's fine, as long as you are happy with your decision. It comes down to how much of a risk you are willing to take with your DC.

With background in science and even doing destruction testing on materials as part of my degree, I've seen first hand the effect that depolymerisation can have and would never take the chance. Its a very personal choice, but I know that I couldn't live with myself if the worst happened and I knew I had put DD in an old car seat.

nicm · 01/09/2009 22:40

cokefan have you thought about a rear facing car seat for your dd? they are much safer and are becoming more available in the uk. have a look at for more info. we have the britax 2 way elite for ds and it will last him until he's 25kgs.

clop · 02/09/2009 03:42

What happens in the crash video? It looks to me like the straps fail and the bottom strap slices the crash dummy in half. How did plastic degradation cause that?

I've been looking at American websites and they seem to say 5-10 years as the guideline for car seat expiry. That's off of reputable sites like and the AAP.

Given how much plastic is in cars made in the last 20 years. why isn't plastic degradation a huge issue in the entire car's safety?

Like I said, it's not the cost that bothers me, it's the horrific waste. Especially for something that has only been used about once a month.

Niecie · 02/09/2009 04:04

Oh dear, now I really don't know what to do. I hadn't considered boosters have a shelf life! I can see that they get worn but hadn't considered the brittleness of the plastic but it seems reasonable.

DS1, just turned 9 yrs, 142cm and over 36kgs has had his car seat since he was 4yrs old. He is getting too big for it yet adult seat belts don't fit him very well (cut across his neck) and I have just been reading how adult seat belts don't really fit for anybody under 150cm. Not only that but being low down when we tried to ditch the booster has left him not able to see out of the window properly and he has felt car sick on longer journeys for the first time in his life.

Now this thread confirms another reason why I need to replace his seat but I can't find anything to replace it with. You would think that there would be such a thing as an adult booster for short people but apparently not.

Anybody ever seen a seat for larger but not large enough adults and children?

clop · 02/09/2009 04:51

Ooh! Finally got an explanation for the video. The straps ripped thru the plastic.
What are the straps made of, that they last so much better than the plastic? I would have thought they were nylon, which is a form of plastic, too, no?

I am wondering same things, Niecie. I could sit on DS's booster, if it's big enough for my ample bottom, why not your DS's, too? What sort of booster do you have for him?

I read (unreliable source, mind) that European car seats are made of much better quality plastic than American seats...

NY Times article questioning the expiry advice, too.

Does expiry date matter with a booster (assuming no LATCH/Isofix/Tether system)? My boosters don't have straps that can rip thru plastic, anyway; the seat belt straps child in, booster is just for correct height, iyswim.

I just found out our Group-1 seat (the 7yr old one) is no longer recommended with lap belt. I'm not really surprised because I haven't been thrilled with the fit for ages. I guess that settles it about getting a new seat, just gotta choose which one, now.

spicemonster · 02/09/2009 07:01

This is one of those things that seems to get lots of coverage in the US but none in the UK. There is no advice when the seats are sold and nothing on any of the government sites. My car seat definitely doesn't have any information about maximum length of use - it's new and I've read the manual from cover to cover.

I wonder if it's because in the US, carseats are likely to be exposed to much greater extremes of temperature in the UK - the inside of a car is rarely likely to drop below -3 or go over 27.

StewieGriffinsMom · 02/09/2009 08:00

This reply has been deleted

Message withdrawn

clop · 02/09/2009 08:37

Apparently the tether strap is coming into EU requirements for new cars soon, by 2012 I think.
In California kids don't require even a booster seat after 6 yrs old or 60 lbs in weight, so it's not always 'safer' there.
You read plenty of stories on American boards about people using ancient seats or no seats at all, plenty of North Americans ignore official advice, too.

The expiry dates /guidelines have got to be based on worst case scenarios wrt degradation, heavy use in extreme conditions.

clop · 02/09/2009 08:39

ps: I don't think it's precisely the law what StewieGM said earlier about having to replace seats. But you can be ticketed for using seats inappropriately or contrary to manuf. guidelines, so if the seat is expired, then Highway Patrol may well cite for it.

StewieGriffinsMom · 02/09/2009 08:58

This reply has been deleted

Message withdrawn

Feierabend · 02/09/2009 09:46

So has anyone got any advice on what type of seat I should buy for my DD1 when DD2 needs to move to the stage 2 seat? DD1 is in a forward facing Isofix Maxi Cosi, which I feel is a very safe but very expensive seat, so I'd like DD2 to move into that and DD1 will need something new. She will be 3yo so I was thinking about getting one of those seats that evolve into a booster. Is there anything wrong with that?

Please create an account

To comment on this thread you need to create a Mumsnet account.