117,00 miles on southern calif Accord EX 4 cyl. auto- I travel around USA so for preventative measures I just put in a nu radiator and radiator cap,water pump,thermostat,upper/lower radiator hoses,all nu heater hoses,coolant,spark plugs,serpentine belt,belt tensioner,air cleaner,trans fluid,oil/filter. I spotted some blue coolant around the passenger side carpet to the left of where your feet are or in the area below the heater core. I put about 8oz of coolant back into overflow container because it was down. Drove it around with the heater on last night and parked it. Opened the hood right then and the overflow was full and carpet was still clean because I cleaned it earlier. This morning with the engine cold I put about two more oz of coolant into the overflow to bring it back up to where I filled it last nite(max level). The radiator was full this morning and carpet was still clean. I have no idea why it leaked some fluid out of the heater core if that is what in fact it did. Is there additional pressure on the whole system when I replace all these items and could that affect the heater core. Any idea how long a heater core may last? I know I don't trust radiators after about 120,000. Any thoughts?