"Expiration Date: Most car seats expire after 6 years from the date of manufacture. If you can't find an explicit expiration date printed anywhere on the seat (shown below), check the owner's manual."
That's what I found online.
I wouldn't use it. The plastic starts to break down, making the carseat unsafe
5 years because the plastic starts to weaken from being in hot cars and during the cold.
I had no idea they expired. That's crazy.
I never knew they expired. My first baby is 8 now and I still have her car seat from 18mos old. I use it for my now 3 year old. Good to know.