coolant- where is it going?

[WE4 WARRIOR]

okay here goes, yesterday while sitting waiting for school bus. scanmaster says 259 degrees, what! check radiator ,low . add water with engine running, see coolant coming from under car on passenger side back by exhaust crossover area on ground. drive car home 12miles/ 20 minutes. put it up on ramps, top off radiator, let car run for 15 minutes. no leaks, temperature stayed around 170 degrees(on way home too stayed at that temp.). drove car around last night for at least an hour- no problems.checked level this morning still full. any ideas. possible freeze out plug, headgasket. no white smoke from exhaust, engine oil is full , no foamy residue. any suggestions. i drive the car as much as humanly possible. thanks for any HELP.

 

[TurboDave]

Could be a leaking freeze plug... or (heavan forbid) a headgasket leak.

 

[mybuick]

might also be a heater core