That's odd... if you're leaking oil the level should go down. Are you sure it isn't another fluid? I'm not familiar with the e30 power steering, but I know on the e36 it loves to leak.
I thought you just had your oil pan replaced/fixed (or was that someone else)? Possibly a botched job?
Those e30 318iS are beasts on the track... hell, they're one of the most fun to drive. Just watch your oil and you'll enjoy the whole day. I know I did!