On my 1988 740 what is the piece that sticks up vertically out of the block if looking down through the intake manifold ? It is leaking oil from the gasket where it is bolted to the the block. My local mechanics are great guys but I find I sometimes have to give them details as to what to order.

Black plastic box with a hose that's attached to the top of it and runs up between the intake runners??? If so it's your oil separator (part of the PCV system), probably not a bad idea to replace it when you do the gasket replacement as they can plug up over time which causes the PCV system to stop venting and pressure up the crankcase.

ETA: Should have said that the whole PCV ie: Flametrap system should be serviced as well as it sounds like your guys haven't been doing it as they don't know what it is or how it works.