About a month ago during my oil level check, noticed the overflow was a little lower than normal. Filled it up to the max level. Yesterday popped the hood to check it out again, thing is pretty much empty. Motor is dry, never a drop to be seen anywhere on the ground. Nothing cloudy in the oil at all, no white smoke from the exhaust. Mechanic pressure tested it at 17lbs, not a squeak anywhere....... We are both stumped. Where the heck is it going? Truck has 55k miles, never towed with or pushed hard really ever.

 

Actually I am having that problem in my 07...I have had the truck a year and refilled it about 6 months ago, and its about empty now. Of course, its not as bad as yours, but it still shouldnt be losing that much

 

Sounds like a head gasket. I just changed mine. I, too, was having my coolant disappearing mysteriously.