Yes, good point! You also have to be careful when loosening the upper line after it has been on there awhile. It is very easy to strip out the threads. A quick test 'just to make sure' yours isn't leaking is to just swipe your finger under the fitting (on the hose) and see if there's any oil on your finger. If there is, have the cooler and related lines R&R'd immediately. Oh, be careful, it will be hot!!
'67 250SE Cabriolet
'93 300E 2.8