Car Seat Safety

Well, lately I have been looking for an extra car seat for Craig's car, we have an extra seat that is in my sister's car since she is our only babysitter and picks up Irina frequently. So just for convenience purposes we would like to have one in both our cars. Craig is very particular about buying used things and isn't afraid to tell me, so he was very against buying a car seat on craigslist. I bought a used car seat at a resale shop when Irina outgrew the length limit on her infant carrier and he only agreed to use it b/c it was in the box with the manual. After reading this I have checked the date and it has 4yrs of life left but not sure I will use it again after all the new details I learned. I called the local fire department to back-up all the information I read on the internet, I never know what I can or can't believe. They all agreed and wished more parents knew about this, here is the info I found useful. Car seats have expiration dates! Did you guys know about this?? I sure didn't! Most car seats expire 6 years after the MFG date (listed on the side of car seats) after reading this I did even more research and learned that plastic becomes brittle, and starts to break down -that can be very dangerous when the car seat is stressed (in car accident). You can't tell if seats have been damaged or cracked so even if a seller says "never been in car accident", who can say if that's the truth?- they just want to sell it and make some cash. Many of these problems can't be seen by the naked eye, so be careful! Also many websites stated that crash tests and data are constantly being updated and used to make changes to car seats so they can do a better job protecting our kids. Using a car seat that is several years old could mean your baby's car seat isn't utilizing newer technologies that could be lifesaving in a crash, or it could be out of date in terms of safety standards. After all this information we are getting a new car seat for Irina, the money will be well spent. Also I attached a video that talks about rear-facing longer and why it's safer. Irina is rear facing and doesn't know any different but I know the difference is for her safety. This is not to make anyone feel bad about buying used stuff, I LOVE yard sales and resale shops and find tons of great deals but I am going to resarch before I buy. I just learned SO much info that I had to share it with yall!!