u need to top it off? hmm... seems u might have a vapor leak. Might wanna replace that RADIATOR TOP and tighten down that water pump and check all hoses.
Mine was doing the same thing for about 2 years and then one day after pulling in for work about the whole contents of the overflow was on the ground. Problem? New radiator from radiatorexpress.com. Problem fixed.
so i finally got around to getting a new cap and it still leaking so i looked under the car and it was leaking around the drain plug as well. but i couldnt tighten it it just kept spinning without gettting any tighter. is there something wrong or will a new plug work fine