Had an interesting situation on a SOAF Viscount in Oman around 1976. Aircraft landed with one engine shut down due to low oil pressure. The engine was changed and on the ground runs the oil pressure was low. The records were checked and this engine had been sent away for repair due to low oil pressure. So the engine was changed again. The next engine was better so the aircraft was returned to service. The next day it landed with this engine shut down due to low oil pressure. The engine was changed again, (lots of spare engines), and again the oil pressure was low on the ground runs, The oil line to the pressure transmitter and warning light switch was checked and found to be gummed up with old oil. After cleaning all was normal. Three engine changes all for a blocked piece of tubing.
Sorry, not really a walk around thing.