ford f350 w/ zf5

[jarmstrong]

i have a 95 f350 powerstroke w/ a zf5 5sp transmission. these trannies aren't known for having their synchros last too long. i don't down shift into 2nd anymore unless i'm stopped.
this tranny recommends atf and i've been using amsoil for the last 57k miles and want to experament with other oils. i was thinking of trying amsoil hdd series 3000 5w30 and see how that does (they recommend it for the nv5600 behind the cummins) and then maybe redline mtl and amsoil 15w40 oil and some of their hydraulic oil. any suggestions?
i also over fill this tranny by about a 1/2 quart.

 

[c_rossman]

If you dont downshift or speed shift the syncros will last a very long time, I would keep using the amsoil ATF, I wouldnt use motor oil as it may be too slippery for the syncros to work right.

 

[mechtech]

Pennzoil Synchromesh is readily available, and reasonably priced [5-6 qt]. It has better gear/bearing protection that ATF, and much better sychro action.
MTL is very good, too.