gringeltaube, those are good points and the measurements seem right, I've never measured mine to be sure. You are correct, not all lubricants are made the same, but I can tell you this.
The oil that leaked out of mine was put in by the military, so it was to military spec. When the oil leaked out of mine it had been driven on the highway at 2400 to 2600 RPM's for over 2 hours before it started to leak. When the clutch started to slip bad enough I had to stop, I left the truck sit, not running, on level ground for about 1 1/2 hours before I pulled the fill plug, when I did pull it, the oil was hot enough and still expanded enough that about a quart flowed out onto the ground...after an hour and a half of sitting!
I can also tell you, that when I drained the oil to pull the tranny, there was no water in the oil. As a matter of fact, the oil was still the same color as new oil, it wasn't even discolored at all. After I filled the tranny back up, I stopped when I could place my finger into the fill hole at the second knuckle, and bend my finger down and the oil came to about 1/2 way up my fingernail. With a ruler, and using a similar thickness piece of metal to bend my finger over this was about 1" down from the hole opening. The next time I drove the truck it was to Columbus and back, a 4 hour round trip at 2500 to 2600 RPM the whole way...NO LEAKS!
Some of you may have good luck with filling to the fill hole, but I can tell you from experience...I DID NOT! Niether did gimpyrobb,
read here (his entire thread can be seen
here). And I was told by too many other members to not fill the tranny up to the fill hole level.
I know we could have a very lengthy and heated discussion about the proper way to maintain the level of the transmission, but the fact is, peoples driving habits and conditions play a huge part in whether the 1/2" space is needed or not.
Some of you like JTugwell and m-35tom might have great luck running it full up, others may not. But I don't want a stranger telling me I don't want to maintain my vehicles properly after I have experienced the problem first hand.
flame away....