did you know that car seats expire?

I have heard such "rumors" and never understood why or how this worked.  Milk expires, I understand this...but car seats?!?   Ok, so I had to be a bit dramatic (who or you are surprised?).  We have stored Ethan's infant car seat just in case we had another child.  I did not realize that his car seat had been manufactured in 1/2006.  I was reading in the car instructions (yes instructions) that the hospital gives to all NICU parents (first time advice mostly) that all infants have to have a car seat inspection and test.  Let me preface this story with the fact that I have installed our car seat and cleaned our car seat in preparation of Aedan's arrival.  I was so excited when they told me to bring the car seat up on Friday for the inspection and test (he has to sit in the seat strapped in for 1 hour to ensure he can tolerate the drive home and still be able to breath, I am sure this is more important with smaller babies and preemies but it is policy for all babies from NICU so we will follow procedure).  I I decided to check our car seat as the manual said that car seats expire....but there is not a expire date on ours...just manufacture date (plus a different manufacture date on the base).   I took those numbers to the nurse for today (we have a great nurse today Jill who will find or confirm any question we have no problems).  She did not know the exact date but thought it was 5 years.  She did know that the nurse next door is the car seat expert (who will probably do ours since she works Friday), who said 5 year said 5 years and that car seat is trash and new car seat is needed.  GREAT! We did not expect to have to buy a new car seat but it is ok...I will do what the hospital suggests and find one I like and will fit our stroller frame *Graco*.  With KaCe is was over the 22inches before he was 3 months.  Aedan is 20.75 inches right now so that will not be the car seat I buy.  I want the 32-35 inch car seat, with 32 lb limit.   He will be in this car seat till he is 18 months or right there near!  Target (just down the road) has a 30 inch one.  Walmart can ship me at 32 or 35 inch one.  Toys R Us has multiple options that I like....but to get to them is quite a drive......but thanks to Casie McNeely (wonderful, wonderful friend) I know that Babies R Us will be having an event that will get rid of the expired car seat and get me 25% off a new one.......but the event does not start till Friday.  I guess I will be talking to Travis tonight to come up with a plan...what to do!!!   Enjoy my comedy and adventure of the day...I will let you know what we decide about the car seats.