Fluid suggestions for high mileage ZF-5?

[MtnHaul]

Well it's about time for a fluid change and my ZF is at 380k without a rebuild and I was just wondering if there were any opinions on a slightly different fluid spec considering the mileage/wear. I've been running the Royal Purple ATF and "If it ain't broke don't fix it" but I thought I'd ask anyway. 3rd gear clunks a little when engaging but hasn't worsened over the last 80k. Tried some straight 30 weight non-detergent some years back and that was a wrong move--way too stiff shifting.

 

[u2slow]

Ford spec is synthetic ATF. I would stick with a flavour of that, or possibly a slightly thicker synthetic engine oil.

 

[XOLATEM]

How many clutches have you been through..?

On the fluid...remember that the syncro rings have to be compatible with the oil...it is not only about geartrain lubrication...

I saw one type of friction material bonded to the rings that was original on an early model ZF and when I got a factory approved rebuild kit another type of friction material was on the rings...

Probably had to do with another type of lube being used to try to dampen the rollover noise...

Early on...it was difficult to get parts for those units...only a couple of suppliers were licensed to sell parts...then later it loosened up...

I am sorry but I don't have a definitive answer for you unless I know what kind of syncros you have...if it was untouched...I would go with factory spec oil.

 

[franklin2]

I would use Dexron VI. I believe that is what zf recommends. That is a full synthetic fluid.

 

[MtnHaul]

How many clutches have you been through..?

I've only owned the truck since 300k and I put in a new clutch and SMF about 60k ago. I think the original owner didn't know how to drive a stick very well as I found 5 or 6 receipts for clutch jobs. My dad bought a 1991 Cab and Chassis F350 and the factory clutch went 290k, throwout bearing was a little noisy towards the end but it kept going.

I'll probably just stick with the ZF spec.

 

[The_Josh_Bear]

I've used Redline MTL for over 150k. Prolly 200k and 12+ years.
This ZF chattered going into 3rd when I got it, but it's lasted this long because of the Redline and me generally being gentle with it, but no grandpa driving here.
I've changed it once 2 years ago. (Maybe one more time but I don't remember)

Anywho MTL means Manual Transmission Lubricant. It's essentially synthetic ATF with friction modifiers to help the synchros. And a bit thicker, but like I said it works great.

I doubt that you'd see a huge positive difference compared to the Royal Purple, just cause that's some good stuff from what I've read. Upside would likely be with the sychros. I'd be interested in a before and after.

Synchromesh and other MTLs are well-touted also. Redline is just the only one I've used.

 

[Old Goat]

Here is another thread on Fluids for the ZF-5.

Amsoil synchromesh in ZF-5

Stumbled across a few quarts of Amsoil Syncromesh on my shelf that I once bought for an NV4500 GM, that I never ended up using. Im due for a fluid change on a ZF-S542 that has some worn syncros and wondering if anyone has had good results. I have heard rumors that it's good stuff. I always...

www.oilburners.net

Goat

 

[ROCK HARVEY]

I used to be a firm believer of the “stick with what Ford recommends” camp, but I did some more digging when I rebuilt my trans about a year ago. ZF-5 transmissions are actually used in many other vehicles outside of the US, they’re even in Chevy trucks down in south america. Outside of Ford applications, ZF recommends their own fluid called “ZF Ecofluid M” which is a 75w-80 fluid for auto or manual transmissions. Redline MTL is a compatible replacement for ZF Ecofluid M, and it’s what I used in my last fill-up. That being said, I think as long as you stick with a quality synthetic ATF you’ll be fine.

 

[ttman4]

Just trying to understand.....
So is fluids like the Redline MTL & Royal Purple ATF, is it thicker than regular ATF? And are they a synthenic blend?
Also what should I be running in my BW 1356 transfer case?
I've always just used regular ATF in my original ZF42 and 2WD, & I'm ashamed to say how many gazillion miles I put on it & was still doing good. However after every hard loaded trip (like from Tx to Or or Or to Tx grossing 30K+etc) I used to drop the tranny & engine oil to service.

After I put this D60 with the donor different ZF42 & BW1356 & have no idea how many miles the donor ZF & BW have/had on them, they shift & do good. I'm still just using regular ATF, but wonder if I'm pushing my luck????
Also this BW1356 has a slow gasket leak in the case that uses close to a qt about 2-3,000 mi. Another project to fix.

 

[rreegg]

Redline MTF seems like a good option - people like it a lot for vw tdi trans but didn't think to use it on the ford (it's a little $$). changed the fluid on the truck a few months ago and went with the oreillys brand atf that should be compatible with zf5 - think it was the "global" or "universal" fluid that's compat with mercon V or something. it's not what I wanted but works fine..

 

[u2slow]

Afaik, the Ford ATF spec for the ZF5 changed to synthetic once they mated it to the Powerstroke. The trans was still a S42 in my '95.

The tcases aren't so fussy about oil. Normally they try to use whatever the trans uses, to avoid cross-contamination in case seals fail.

 

[IDIBRONCO]

And are they a synthenic blend?

Nope. MTL is a full synthetic. You may have to zoom in to see it on the label. It's to the right of Red Line and above the "TL". I believe that Royal Purple is a full synthetic too, but I'm not sure on that.

 

[Old Goat]

Those Red Line bottles make great funnels.
Don`t have a ZF yet, still reading the oil debates.

Goat

 

[ROCK HARVEY]

In the past I’ve used the Valvoline full-synthetic ATF in both the zf-5 and the 1356. It’s the one in the red bottle and they have it at my Walmart for like $25/gallon. I think that’s the best low-cost option.

Now I run MTL in my zf-5 and motorcraft mercon LV (not mercon V) in my 1356.