I have had red tops in a few vehicles and now have two yellow tops in my diesel. I have noticed if the red tops sit for a time they go dead (like most batteries would) but something happens to them and they can't hold a charge anymore - I have replaced 3 Optima batteries under warranty because of this. They always try to charge it to see if it will hold a charge then replace it free when it doesn't. The yellow tops on the other hand have sat (not my fault - I learned), gone dead, and been recharged and have held a charge for quite some time. I have had no experience with blue tops.