Gearbox lube revisited

After reviewing Mr. Mik's posts about gearbox lubes he tried, I thought I would take a look in the gearbox on my Vectrix. My gearbox is fairly quiet and I actually test drove all the Vectrix's the dealer had in inventory to get the quietest one (turned out to be the demo). Upon disassembly, with 500 miles on the odometer, I was suprised to find the gears in very good condition. Unlike Mr. Mik's Vectrux, the planet gears were clean with no pitting on the tooth faces. Also, there must have been a design change in the ring gear as it is different in my Vectrix from the gear in Mr. Mik's. Where Mr. Mik's Vectrux has a gear with "tabs or tangs" on the outer diameter of the Ring gear, there are none on the gear in my Vectrix. The outer diameter of my ring gear is smooth and therefore much thicker in section then Mr. Mik's. This would lead to a gear that could be held to a better tolerance during manufacturing and would maintain a more constant shape when heated in operation. When I withdrew the factory oil I was only able to remove 60 ml. I used a large syringe with ml graduations on it and got every drop. Mr. Mik said he thought the fill was 80 ml so on refill I split the difference and put in 70 ml. As to the oil---I was not so interested in noise, but in range and every little bit helps. I found a extremely low viscosity oil (about the viscosity of diesel fuel) designed for the GM-EV1 gearbox. The EV1 gearbox was splash lubricated with a mixture of spur and planetary gears, handled over 100 hp with motor speeds up to 10,000 rpm---so I am going to trust it in the Vectrix. The bottle says: *For electric Vehicles *Reduces viscous drag *Increases vehicle range (what more could one ask for). It was GM Part # 12371288 but is no longer available. Lucky me I had several pints of it left over from the old EV1 days. The new oil doesn't seem to change the noise of the gearbox with the exception of a slight "rattle" from the gears between drive and coast loading. I wish I had a current meter mounted so I could see if was any change in load at various speed with this oil. I am going to run it 500 additional miles and see whats going on at that point. I am also going to cut a set of helical gears to replace the spur gears this fall---then the Vectrix will be stealth!