4 qts of oil lost in 1,000 miles??!!

My '83 308 QV runs great, does not smoke (ever) and drips some oil (or trans fluid, I'm not sure) when parked. I recently checked my engine oil level again when I began noticing the pressure staying down under 3 bars most of the time and almost nothing (1 bar) at idle. Checking the engine oil level I was horrified to discover it needed over 4 qts to bring in into view on the dip stick. This after only about 1,000 miles of conservative, sometimes briefly spirited weekend driving. I'm mad at myself for not checking the level more frequently. I sure will from now on - at the start/end of every drive! I probably should pull the plugs and check them too.

A mechanic friend (NOT an F mech) told me it's possible the engine oil may be seeping into the trans section (i.e. not burning it or leaking on the ground) and to check the level there. I will do this ASAP to check on it anyway. However, is this a possible cause of loosing oil for this model car?

Are there any other possible causes of loosing this much or is this "normal" for a 25 yr old engine with 24,300 miles on it. What else should I check on?

Thanks.

Bob R.