What would cause my 2002 Altima to consume oil, and how can I fix it, economically?

I have to put sometimes 2 quarts of oil in my car a week. It is burning oil bad, and when I check it it is black, even a few days after changing it. There are no leaks anywhere.What would cause my 2002 Altima to consume oil, and how can I fix it, economically?
More than likely you have bad/worn rings. The only way to fix it is to rebuild/replace the engine.What would cause my 2002 Altima to consume oil, and how can I fix it, economically?
Please E-Mail Me at jp.hudson@sbcglobal.net Additional data like miles and vin# will be helpfull. We need to talk!
You need an engine. period. Don't try to rebuild an aluminum engine.
I'm not sure what is causing it. I know nissan had some problems with older altimas burning oil like that. Take to dealer.They seem to have corrected the problem now. 2004 and older.
rings, valves, maybe a small campfire in the oil pan
Blown cylinder head gaskets?