Fluid type in 1989 ZF5 and transfer case lubricant

[Jbone36]

89 f450 Zf5 4wd...Not trying to open a can of worms but i keep getting different information from mercon in both to gear oil in both to 80 in diffs and transfer?..my shop manual is missing transmission requirements, thanks

 

[CDX825]

ZF5 takes ATF. Transfer case will be the same. Diffs were probably both speced for 80W90 but you can run 75W90 as well. At some point in time they switched to 80W140 in the rear diff but unless your towing heavy a lot 80w90 or 75w90 will be fine.

 

[TNBrett]

I run Royal Purple Synchromax in my ZF5 and am very happy with it. It feels like it makes it shift smoother, and maybe makes it a little quieter. The Transfer case gets ATF, but I would look for a synthetic Dexron III/ Mercon spec fluid. The newer Dexron VI/ Mecon LV fluid is significantly lower viscosity. That’s good in an automatic transmission, but not necessarily beneficial in a manual transmission or a transfer case.

 

[MtnHaul]

I've run Royal Purple ATF in the ZF and t-case for the last 55k and like the way they shift. I briefly tried running non-detergent 30wt in the ZF and the shifting was horrid compared to ATF. FWIW I have 366k on trans and t-case which the PO of my truck kept changed with regular ol' whatever's on sale ATF.

 

[ISPKI]

http://www.wolfshead.com/universal-synthetic-atf-qt.html

This juice has never failed me in either transmission or transfer cases.

 

[Jbone36]

AtF it is then..funny the amount of people running 80 90 ..quick google and i picked some up cause my old fj used it after a bit further search it seemed alot people were confused like me. Thanks all for clarification.

 

[IDIBRONCO]

it seemed alot people were confused like me. Thanks all for clarification.

From my own not-very-detailed observations, it seems like a manual transmission with a cast iron case takes 80/90 while one with an aluminum case takes ATF. DO NOT take that as gospel by any means, but it seems to be what I've seen.

 

[ttman4]

From my own not-very-detailed observations, it seems like a manual transmission with a cast iron case takes 80/90 while one with an aluminum case takes ATF. DO NOT take that as gospel by any means, but it seems to be what I've seen.

This is the info I've gone by for several yrs. Iron case = 80/90 while aluminum case uses ATF.
My ZF alumn & my BW 1356 alumn transfer both use ATF

 

[WAID]

From my own not-very-detailed observations, it seems like a manual transmission with a cast iron case takes 80/90 while one with an aluminum case takes ATF. DO NOT take that as gospel by any means, but it seems to be what I've seen.

For a not very relevant to tgis forum exception, my Aluminum cased Toyota manual takes 75w-90.

 

[The_Josh_Bear]

I run Royal Purple Synchromax in my ZF5 and am very happy with it. It feels like it makes it shift smoother, and maybe makes it a little quieter. The Transfer case gets ATF, but I would look for a synthetic Dexron III/ Mercon spec fluid. The newer Dexron VI/ Mecon LV fluid is significantly lower viscosity. That’s good in an automatic transmission, but not necessarily beneficial in a manual transmission or a transfer case.

Similarly, I have run Redline MTF for 13+ years and around 100k on my rig. At the time I did that the syncros weren't very good with 1-2 being the worst and would always chatter going into 3rd.
Considering I'm still running it(having changed the fluid once) and still have the same transmission, I am very much a believer in this product.
It's now time for me to seriously look into rebuilding mine or buying one, but I'd say that's pretty darn good for the state it was in when I bought it.
MTF stands for Manual Transmission Fluid and is basically synthetic ATF with other modifiers that help the synchros, as far as I can tell. I'm sure there are other benefits but the point is, it's a purpose-built lube for this type of gearbox.
Edit: It's MTL. Manual Transmission Lube.

 

[IDIBRONCO]

I have run Redline MTF for 13+ years

I'm only finding Redline MTL. Is that the same thing?

 

[The_Josh_Bear]

I'm only finding Redline MTL. Is that the same thing?

Oh doh. I was running off memory, and that's what I get!
MTL for the win. Manual Transmission Lube.

 

[ttman4]

Quick question. Where you guys find Redline MTL or the Royal Purple Synchromax? I haven't looked round much, just been using regular ATF in the ZF & BG 1356 transfer.

 

[The_Josh_Bear]

Quick question. Where you guys find Redline MTL or the Royal Purple Synchromax? I haven't looked round much, just been using regular ATF in the ZF & BG 1356 transfer.

First time was at a local Toyota Dealership as my buddy works there and they are a redline supplier.
Second time was online. Whoever had the best price of stuff+shipping. Here's the best deal on Amazon I could find:
1 gallon Redline MTL ($56, actually a pretty good price with free shipping. That's $14/quart which is about what I've paid each time)

 

[TNBrett]

NAPA or Amazon for the Royal Purple. I have a NAPA just a block away from my office. This is one of those things they don’t normally have in stock but can get in an hour or two from the warehouse.