Congrats on being back with your E9. First, five months I do not regard as long period rest. In Germany, almost all classic cars sit for five to seven months each year because of unfriendly conditions outside. We are used to this. Your car probably was sound when you last used her so there is nothing much to worry.
A good idea may be to look for water or oil stains on the floor under the car prior to moving or even starting it. That way, you know where it came from. Some people aroung here still use the routine
@Dick Steinkamp and
@stphers describe. However, leaving a car standing at idle is not recommended anymore, in Germany it can even get you into trouble with neighbours or the police.
A starter motor in good order takes a minute of work without complaint. By then, the engine should fire up, and you are ready to go. If you want to be very careful, rev not over 2500/min for about seven miles, then not over 3000/min. Apply the brakes a few times (hard) to check for proper function. At the first filling station, adjust tyre pressure and check for leaks again. Once there, play with the lights, wipers, horn, fan etc.
When the oil is warm, takes 3x the span the coolant needs, you may go up to 3500, then 4000, and after 30 miles full throttle. Don't forget to cool the engine down on the last seven to ten miles before turning the engine off.
That said, I don't know about American petrol, the kind of oil you use, and Weber (one b, pray you) carburettors. My suggestions may work better with European cars than with USA versions.
