Losing Coolant

Do a pressure test on the cooling system. This will allow you to find the leak on a cold engine. Sometimes a small inspection mirror helps to look in the tight places. I would start with looking around the water pump. If you find any signs of coolant leaking out weep hole even if it's dried old coolant replace the water pump cause it is about to fail you. Hope this helps

Thanks. My mechanic did. He saw no leaks. So I went to dealer and they said engine was fine and it was the hoses which were old/original. However the problem still exists.

I found this info concerning your model vehicle. "Watch for coolant leaks from the radiator, where the metal fins meet the plastic “tanks” on either side. " --- http://www.autofocus.ca/cars/hyundai/2006-hyundai- tucson/2006-hyundai-tucson-4dr-gls-4wd-27l-auto/reviews/reliability- report

The most common cause of "mysterious" coolant loss is the radiator cap. Most times the cap seal is cracked or worn and coolant is lost through it as evaporation. Another possibility that won't show up when pressure testing the radiator is leakage from the overflow reservoir.

Check the freeze plug in front of the engine.They can develop a leak over time, a small leak but you couldn't see it because the engine mount is in the way .