I just bought a 98 C230 with 58k miles. Can someone explain how FSS relates to service intervals and the same with A & B service. Is FSS an onboard system that determines when certain maintenece is needed and is it OK to overmaintain because my wife and I like this car!! I noticed the wrench symbol flashing when I start the car and it also says -1000. I changed the oil this weekend. piece of cake once I found a wrench that would work. I had to stuff a rag in it to keep it from slipping. I guess i will cancel the one I order from the dealer.