might just be condensation in your exhaust system.But if its using water things dont sound good.Any other symptoms such as mayo round the oil filler cap?
Do a compression test on it: you'd be mazed at the amount of condensation oil can pick up. Also check for leaks from the water pump when it's warmed up.
coolant levels aside
white smoke [its just steam I think] is normal for this time of year, especially so if the car isnt driven enough to get the exhaust hot all the way through.