Strange thing has been happening recently with my '80 245... The Oil keeps disappearing...

I'm fairly sure it's not leaking anywhere... Have found no oil under the car. The oil must be going somewhere. I keep checking the dipstick, and the level just keeps getting lower and lower.... Plus, there seems to be more exhaust then usual, but that may just be because of the cold weather....

What would cause oil to burn anyway? What does that mean if oil is burning? I've never had to deal with this in a car before, so I don't know much about what causes it, or what to do about it.

Maybe it's not burning oil, (I can only hope,) but what else might it be? What are common places that the oil would leak from?

I've gotten 250000+ miles out of this thing, and plan on getting 250000 more, even if I have to buy oil every 2 weeks!