I noticed on the first cool morning last fall that my starter didn't spin the motor as fast as it had, but it always started fine. I live in the south so we didn't have much of a winter and it never caused a start problem all winter. This past week I parked the truck for 6 days while on a boat trip and the 5 year old original batteries officially died. I had to jump it and immediately put in two new batteries. I was limited on my choice since I was in a very small town and the only available batteries were from NAPA. They had them, the price was good so they are now in my truck.
When I made the first start I realized how bad my old ones actually were. The difference was amazing.