My wife's 2003 Hyundai Santa Fe (2.7L) seems to be losing coolant. When I was changing the oil last weekend, I noticed that the reservoir was just about empty, so I filled it to the full line. I took it to a mechanic who pressure tested the system as well as the radiator cap. He said everything checked out fine and he couldn't see any leaks. We drove it for a couple of days and the level got toward the Low line. I filled it to the full line. A couple of additional days, and the level is sitting halfway between low and full. I filled it back to the Full line last night. Basically, I've added probably a couple of quarts over the last week. I can't see it going anywhere. I do not believe that it is going into the oil, because when I changed the oil (at around 7000 miles on Pennzoil Platinum) the oil looked fine. It wasn't the least bit milky or anything to indicate a coolant leak. For now, I'm stumped. The mechanic said if it kept losing coolant to bring it back and he would do a dye test. I'm just curious if anyone out there has had a similar issue--especially with the same engine--and might have some insight. I'm going to continue to drive it, watch the coolant level, and check the engine oil. The car runs/drives fine. All comments are welcome! PS. I've been checking the levels with the engine cold. I've been consistent on that.