I'm not a mechanic and could really use some insight here. My '73 240z drips oil when it's running but not after the engine cools down. It just started doing it this spring after it had been in the driveway for a couple of cold months (had to move it out of the garage due to some house remodeling). Any idea what could be causing this?

Where does the oil drip from? Could be a front or rear crankshaft seal since they wouldn't leak when the engine isn't running and the oil has drained back into the pan.

Stephen could very well be right.... You could also check around the cam cover for a leak, or perhaps loose bolts at the fuel pump where it attaches to the head. You'll have to do some poking around to track down the origin. Where is it dripping at? And is this after it has been 'driven', or just sitting there warming up? Feed us a few more clues.

Thanks, I'll poke around a bit. It appears to be dripping from the point where the transmission is connected to the engine. I don't know if that's because it's the lowest point (gravity) or the leak is nearby. I can tell it's dripping when the car is running because there are drops leading up my driveway. There is also a fairly large stain where it continues to drip once parked. I'll check it out further, thanks for the advice!

That's the area where a rear crankshaft seal would leak.

Could be the front seal on the trans as well. What does it smell like and what color is it?