My buddy's 96 SS was about 1/2 gal low on coolant, enough to warrant the Low Coolant light on the dash. Haven't found any leaks, no puddles on the ground, and no signs of the resevoir tank bubbling over. Could it simply be coolant burned off much like oil consumption on LS1's??

 

have him try a new radiator cap, I would have to fill up on coolant every week or so, then I replaced the cap, I havent put coolant in her for months now and its full as when i last filled it.

 

any white smoke out the exhaust?

 

Check for white smoke. If not, check your spark plugs. If any of them are clean, then he probably blew a head gasket. That happened to me, and it ended up being a blown head gasket.