Today I removed the filler and drain plug on my transaxle (Porsche G50-01) and was surprised to see how much gear oil drained out into a pan-- two tablespoons! The guy I bought it from must have drained the tranny to lighten it for shipping many moons ago.
I put in three quarts of Red Line 75/90 NS synthetic gear oil with a little China Freight hand pump. Trying to get a funnel into the filler on the side of the case wasn't working but, fortunately, I found this little pump for $6.99 on sale. It actually worked quite well. To be sure of having a high enough oil level in the case, I'll buy another quart and put that in as well. Since this transaxle is running upside down, the usual oil capacity doesn't apply but the GT40 replica people are using 3 to 5 quarts so I think 4 should be OK.
Next came a vent tank (AKA "puke tank" to the Good Ol' Boys) to catch any oil blown out of the top tranny vent. I had a nice little aluminum tank from who knows what originally that looked perfect, except that it did not have a breather. Fortunately, I had one of those, too. It had a pressure/vacuum release button as well as automatic venting. The pressure spring was too strong so disassembled it and cut the coils down so that very little inside pressure would open the vent. If it took too high pressure to open, gear oil might be forced past the tranny seals and leak.
To mount the breather, I cut a 1" hole in the top and epoxied the mounting nut to the tank. The bottom is a drain fitting and a side #4 AN fitting will go to the transaxle vent. Next I'll mount the tank to the chassis.
Regards, Neil Tucson, AZ