So I decided to drain and refill coolant in 2001 tahoe we have had since around 2002. I thought I had changed this several years back but I don't have any record of it and I keep good records. Never had water pump,coolant leak, or anything for that matter.knock on wood. Only thing different under hood is couple new batteries and couple air filters over the years.. well coolant came out very clean, color looked great,not rusty or discolored. There was little sediment in resorvoir which I took off and cleaned out. Also just little sediment in drain pan but not much. I filled with 50/50 mix of super tech amam. That's all I had in shop handy so that's what it got. I will do another drain and fill soon and call in good. But any how I'm really impressed with this dexcool considering how long it's been in there and really feel I could have just left it.