Ken, I have been reading your trials and tribulations with interest. I had a funny experience many years ago which might just have a connection. As a student I overhauled the engine of a car in a hurry and left on holiday without testing the car. After 200 miles the oil light came on, (it was nearly midnight). Opened the hood, no major oil leak, just a little oil on the dipstick. After close torchlight examination I found the problem. The dipstick on this car is in a tube on the outside of the engine which connects to the bottom of the sump. In my haste I had twisted the air cleaner and kinked the rubber breather tube. The crankcase pressurised and blew all the oil out. One twist of the air cleaner and a kind donation of oil and I enjoyed the rest of the holiday. This is where the link comes in, is crankcase pressure not somehow pushing the oil back into the gearbox?