I'm planing on getting my transmission flush and replace with some good quality oil, hopefully it can improve shifting because I'm getting grinding when shifting from 1st to 2nd when the engine is cold. it's a 2005 evo 9 JDM six speed gearbox, I just need some advice on what is the best oil to use for the transmission?
Also do I need to replace the transfer case and rear diff, ayc oil at the same time? If so do they use different oil?

 

Honestly you really didn't need to create a whole separate thread for the same issue. I already recommended you a fluid mix to use, as did others in your thread. I've replied further in your thread.