Just got myself and brand new old truck. I got a 97 4x4 with the zf5 and am going to change trans and transfer chase fluid this weekend. I have seen a lot of threads about about people putting different fluids other than atf and different additives.

I will be going with the recommended synthetic atf.

Is there an additive that helps extend the life of the synchros and the rest of the trans. There seems to be a lot of threads with a lot of different opinions. I even found one against Lucas which is what I was thinking of adding.

What do you use and why.

 

i use the royal purple syncromax oil its designed for manual transmissions and transfer cases that were originally service by atf. my shifts are much smoother with that vs atf

 

Straight up Synthetic ATF. No snake oils here