Recently, after traveling approximately 600 miles in my 2004 XLR, I experienced a loss of one gallon of coolant from the closed radiator system. The dealer checked the vehicle over and said it was not leaking. Has anyone else experienced this problem? Could there be a problem with the aluminum engine heating up and excpanding and the steel bolts holding the engine heads down causing coolant to escape into the cylinder heads and evaporating during the combustion process?