how long is car seat good for
1 Infant car seats have a service life of 6 years. 2  Convertible car seats (excluding the Classic line) have a service life of 7 years. 3  ClickTight Convertible car seats have a service life of 10 years. 4  Harness-2-Booster seats have a service life of 9 years.  Belt-Positioning Booster seats have a service life of 6 years.