Engine Oil in Transfer Case?

[Willys LJ]

I was trying get some basic info on my transmission and transfer case (oil capacity) the other night and went to Novak's research pages. There it said that some have been using 30w or 5w30 engine oil in either regular or synthetitc instead of ATF fluid in the NV231 transfer case. They claim that in their and their customer's experience "indicates "positive results in noise reduction and wear resistance".

http://www.novak-adapt.com/knowledge/transfer-cases/np231/

Anyone know anything about this?

 

[pagrey]

I read that and use 15W-40 in mine. It makes less noise in 4LO especially when you are moving at any speed. The 231 doesn't seem too fragile, I don't think it cares either way. I use 15W-40 in the summer in the engine so I don't have to carry any special oil for the transfer case on the trail. My experience is one case with less than 30K so I wouldn't take it as proof of anything with respect to wear but it does reduce the whine a bit.