Nissan Repair: 2002 Altima 2.5 SL antifreeze consumption, engine bearings, blown headgasket

Question
My 2002 Altima 2.5 is consuming antifreeze excessively. I'm aware that the heater core is blocked because I hear a swishing sound when I'm in the vehicle. I'm having the car serviced tomorrow to unblock it.  I'm adding almost 500ml a week depending on how much I dive it. I've looked for leaks but didn't find any. Where is all the antifreeze going?

Answer
Domenic,

It could be that the heater core is leaking at highway speed and as such you do not see the coolant coming out since it is only doing it on the drive.  Second is worse as it could be a blown headgasket.  If you start the car go around to the back and see if steam is coming from the exhaust.  If so, you have a leaky headgasket.  Also, check your oil to see if there is coolant in the oil.  Sometimes, when a headgasket blows it will allow water to get into the oil.  If this is the case get it repaired soon as coolant in the oil will trash the engine bearings.  Email me back with what you find.