the water in my radiator resovoir(if dats even wut its called...u kno, the clear plastic thing next to ur radiator) keeps disapearing, i dont think thgeres a leak cuz i dunt see any leaks visually, cud it be boiling it away? my car doesnt have any overheating problems so i think everything is working fine...i dunno if this amtters but since its summer i just been adding water in there so the mix is prob like 75% water, i remember hearing somewhere that the collant actually helps raise the boiling temp too, cud dat be causing this? im not having any problems with the car but i just wunt it to stop stealing my water

 

Before you start your car in the morning, take off the radiator cap and try to get an idea where the water level is (in the radiator). It is abnormal having to keep adding coolant every few days, Either you're loosing coolant from a hose connection high up in the engine compartment in the form of steam, or you're loosing coolant from any one of a number of hoses, components (radiator, heater core or hot water control valve) and possibly water pump.
The coolant level you find in the radiator can be a hint as to what level the leak is at.
A cooling system pressure test is in order.

 

I agree ::

There's a leak somewhere definately. And the water is not boiling away because the caps hold 16 lbs of pressure which can be reached at 195 degrees F or higher. So if the water was boiling (212 degrees F) the cap would be gone.... It could be the cap, also, try replacing the radiator cap, it may not be sealing. But you should find that out with the pressure test. Also, be sure to flush your radiator every so often. Old coolant can get gummy and thats not good. You can buy radiator flush at any auto parts store. When you get this sorted out, you need to flush the radiator (follow the directions on the bottle of flush) and then fill it with whats called "50/50 Coolant/Antifreeze"