I asked that question also. The reasoning is that they don't know how long the engine has been sitting, so they would rather do it as a preventative measure. I've also had oil going through my cooling system so I'm not super opposed to it. In the grand scheme of things it's not that much more money, and since they are going to warranty the parts I'd rather do what they recommend.It seems odd to me that they are changing the water pump on an engine with only "6000 miles" on it. Yes, it's easy to do while the engine is out, but it sure seems like changing a part just because you can. Hmm...