The light kept blinking. Oil level was full and very clean; in fact, the
unit had just been thru its very thorough annual servicing just two months
earlier. And so it went to the shop where they changed oil and installed a
new filter. A note on the invoice said, "Oil light will stop blinking in 3
hrs."

Sure enough, it did stop blinking although much earlier than 3 hrs. What
was the cause for the blinking oil light? I was expecting them to say that
there was some problem with the oil being pumped into the moving parts, but
there's no mention of oil pump failure or anything like that.