just wondering what is a good weight for the transfer case np 205. synthetic or dino. what make.also for both front and rear diff whats the best oil to use. thanks

 

I am ordering oil for my tcase and diffs as we speak.

amsoil severe gear 75w-90

 

A NP205 is happy with just about anything in it, so long as it isn't water. Over the years they were speced for 40wt engine oil, straight weight gear oil, 75W90, 80W90, GM even ran ATF in them.
Your favorite gear oil will work just fine.

 

This is what I run. FSM for my 93 says to use 10w30 motor oil

 

Oversized gears, huge bearings and a very tight clearance makes the NP205 a bullet proof unit. Keep the water out and use a nice oil and you're set! Also make sure after each change you clean up the particle magnet through the PTO cover and create a new gasket.

I use lucas oil, anything will work though. Most important thing is to check it