Another Update: After a couple a days running out for trips etc all looking good after 100+ miles.
Nest question is why did the oil pump loose prime in the first place?
In 36 years of ownership and sometimes well over 6+ months between starting the car why did the oil pump loose its prime?
Only data point is I did an oil and filter change some 35 miles before it was put away for 5 months, the drive immediately before it was put away got the oil very hot.
Only thing I can think of is the oil filter (now changed) had an issue with the non-return valve?
I will take the possible offending item apart in due course to investigate further.
Let hope it last for another 36 years!!
The main thing is that you managed to solve the issue.... As for the cause, it seems you did not find anything obvious, which ever leaves one wondering... I know that feeling, with a recent battery failure..!
I suspect the issue is ever likely to be caused by drain down over time when a lengthy period of lay -up is involved, other than that draining the oil and changing the filter together can accelerate the the drain down process, add potential oil pump wear, pick up, and strainer issues any and all of which can effect pump efficiency, and you are back to square one...
My old +8 suffered the death watch rattle of empty hydraulic tappets, during start up after an extended lay up a decade or more back, and it seems to have suffered no real issues that required further investigation and still runs just fine. I suspect best to worry a little less and just enjoy the drive...? (-:
All be it monitoring oil pressure over time to gin confidence that all is well..
Wishing you many happy miles..
