I have just bought a 1993 F-350 duelly, with a 5 speed trans., which I assume is a ZF. I understand that the trans takes ATF. I would imagine that the best would be a synthetic. Are they all the same weight? I'm in a warm climate all the time. How about the rear end, does that also take ATF or gear oil? Whatever recommendations you guys could make, would be greatly appreciated. I'll be keeping this truck for a long time. Right now it only has 45,000 miles. Thanks.

 

Synthetic ATF would be a good choice for the trans. Look for one that meets Mercron V specs. such as Mobil1 ATF.
For the rear diff you need 80W90 Hypoid gear oil. If you want you can go syn. there as well so long as it is a Hypoid gear oil. However check if the diff is limited slip or not because if it is you would need to get the 80W90 Hypoid gear oil with the limited slip additive.

 

Thanks Lazy K. I'll look for some numbers to see if the differential is limited slip.