Transmission fluid type

[mpatch]

I have an 89 grand wagoneer and was using dex/merc after a transmission fluid change and when checking the fluid level . But when I went to a local auto parts store they said there computer was recomending a different type. My question is should I be using merc for transmission fluid..transfer case and power steering? All the same or something different? They recommended atf+4 for transmission fluid. I used dex3 for the transmission fluid? Would that cause harm and i dont think the owner manuals was calling for atf-4 but maybe i was wrong.

[carnuck]

The ATF+4 is more expensive and same coverage as Dex III. (somehow the last part didn't make it from my brain to my fingertips before posting)

[FSJ Guy]

Dex 3 is FINE. Dex 4 would probably be OK, but you don't need it. Don't listen to everything the parts store computer tells you. Of course it's going to recommend the more expensive fluid.

IIRC, they're up to Dex 6 or so. Only the newer transmissions need that. Your old 727 will do just fine on Dex III.