If it seems watery, then I would say it's leaking coolant/antifreeze.
Things to have them look at are, the radiator, hoses or the water pump. These are all places that could be leaking.
If the coolant gets too low it could cause the engine to overheat, so make sure you get this problem looked at.
〉 Answered on Feb 14th, 2008 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines