After about 5K miles, a warning light came on showing "Low coolant". Took it into dealership for it's first oil changed and noted the warning. They just called me and said they found coolant leaking into the engine because they found a couple of plugs. The exhaust smoked when I'd start it (grey smoke). They said there shouldn't be any problems because they've fixed the plugs and changed the oil. My gut tells me that any water residue inside the block, manifold or cylinders is going to cause problems down the road. They are telling me not so. What's the truth?autocom cdp?