Jacking up the car is not strictly necessary to change the oil on all E30s. I have lowered my car, so a drain pan will not fit under it as it sits on the ground. When my car was at stock ride height, I was able to change the oil without jacking it up by using a low profile drain pan.

You may also wish to put chocks behind the rear tires to keep the car from rolling. My emergency brake system is brand new, so I don't usually use chocks. If you are unsure, either use your factory wheel chock or put a brick/4x4 behind one of the rear tires.