are you 100% positive its not leaking? :dunno:
i had a similar problem with my car, it used to loose about a quart to a quart and a half every oil change (about 3k miles or so) and at first i thought it was because i was constantly revving the car up to redline, but i was wrong. turns out the valve covers were leaking from the back, where i could hardly see it, and it never made it to the ground, either getting boiled away on the block or the trans. never noticed it until i did a clutch job and couldnt figure out why the trans was glued onto the block (coolant and oil leak = glue). also, on mine, the gromments for the valve cover bolts were leaking a bit, but those only got the oil to the cylinder valley where it boiled away and i pretty much never noticed it as well.
i would say double check to make sure you arent leaking oil. if you arent burning it, and you arent leaking it, there should be very minimal oil loss between oil changes.
oh, and by the way...........wtf???? you guys have a low-oil light? mine doesnt, and ive been about 1.5 quarts low before too :crying:
ps. faulty valve seats can leak very little and you wont be able to see the bluish smoke coming out of the tail pipes because its such a minimal amount, but this equals to about .5 quart ever oil change.