Petrol station
If my memory is correct it was just outside the terminal building. If you exit the current door opposite the international arrivals next to the parking ticket machines, cross the road and you would be on the land where the filling station was. It was also an Avis car rental station.
Could you imagine a public petrol station so close to an airport terminal now!.
If you looked back to the terminal you would probably see a BKS Britania or Viscount. Not to mention a Dan Air DC3 or Airspeed Ambasador billowing smoke in the air on start up, and possibly a BUA Visc used on the Ams route in those happy days.
Sorry about that. Fond memories (poor old soul!!).
Think it closed as a petrol station over 30yrs ago but continued to be used by Avis for some time afterwards.