I have coolant disappearing, the expansion tank is now 1 1/2" below min. I saw it was low (slightly below min when hot) a few days ago and assumed it was poor prep. I have to take it in next week I was going to have them top it off. I put about 100 miles on today and it was noticeably lower when I returned. I only have about 600 miles on it so far. Nothing visible anywhere I can see in the engine compartment or underneath. Nothing visible has dripped in my garage. No smoke from exhaust, engine runs amazingly well, oil on dipstick looks perfect. Any ideas? Anybody else had similar problem? I'm thinking maybe a small leak somewhere dripping onto something hot, which is why there's no evidence of leaking coolant?