at 6500 miles the coolant reservoir level has decreased from the 'full' mark to a point about 2" above the 'add' mark. No evidence of leaks, but, used the ac/heater for the first time last week. I check under the hood at least once a week for abonormalities and coolant is always full. I will check oil level today but wanted to ask if the heater core might be empty at the factory, only filling when first used? I have no 'signature' yet, but the '05 is Q. C. /4x4/G56/LWB and runs/rides like a dream. Well, it doesn't exactly ride like a dream...