IIRC, the primary reason for the 50K change interval is Ford's use of regular ATF. GM went with synthetic (along with no pump / cooler and IIRC helical gears) and their ZF-6 spec has a much longer change interval.

And good to know that your ZF is still gong strong

 

And question: what problem are we trying to fix with the tranny filter? Even the narrative in DieselSite makes this look like a 'just-cause' solution . . . The only known issue that I am aware of with the ZF-6 is replacing the DMF with a SMF.

A coolant filter I can understand as there is a known issue.

 

Sorry to be a dummy, but what is a "DMF" and what is a "SMF"?

 

Dual mass flywheel...single mass flywheel. Mines an oem SMF(L99).

 

We can use synthetic in ours too. I tried it a few times. I just didn't see the benefit in it. In my climate, I actually prefer a little synchromesh mixed in with the ATF.

Besides, how much longer of a change interval do you get with synthetic? And is it really that big a deal to change the fluid every 50k?

I bet if I ran an used oil analysis on my dino ATF they'd tell me I could go longer than 50k too, but why be so stingy? Every 50k isn't really that often. Even for me.

 

Thank you sir. I guess mine is a single mass flywheel too. (Just had clutch replaced.)

 

Yes we can reliably use synthetic, and No, cracking a couple of nuts, draining the old, and pumping the new back in is not all that a big deal

Granted, the benefit of synthetic lube is a matter of preference (even in the other locations) and playing with extended drain intervals is also a matter of personal preference. Point of the Ford verses GM's ZF lube type and change interval is to highlight that Ford apparently had concern with the effects of heat on the ATF. In GM's case, they decided to go with the more heat tolerant synthetic and IIRC there is no change interval (ever). Just to test the memory, I just pulled an owners manual (2004 Silverado 2500) and it only calls for a change to the clutch fluid every 25K mi and no stated interval for the tranny's fluid. Definitely not looking to start anything with the observation, just stating comparisons.

For me, each time I swapped one of the components over to synthetic I saw an instant increase in mileage. When I did it in the tranny, did not notice any difference in the shifts. So, sure a benefit of increase in mileage is questionable in terms of immediate cost recovery. My focus for the lube is on lowering parasitic drag which leaves more power for pulling the RV and other stuff. But all of this is a little OT.


Toward the topic, seems that there is no clear reason to use an auxiliary filter for the tranny fluid other than personal preference, correct?

 

Please take this comment as trying to be helpful to a group of men that have taught me almost all I know about my truck. First Thank you again. I installed a transmission filter like this, checked the fluid fill to ensure it was full and it was. Six months later I hear bang bang sis boom ba. Bottom line is the tranny was out of fluid. I found a transmission repair shop in Pennsylvania whose owner stated that he bought the inventory of a shop in Canada and would import new ZF 6speed transmissions on an as needed basis. It cost me $3000 for the new one that a friend and I put into the truck. It was my friend who told me to forget about filling it from the bottom. He said take the shifter off and dump six quarts of Mobil One Synthetic Transmission fluid into it and call it good. The rear main seal is leaking now but the transmission is good.

 

2 things.

Did you figure out where the leak came from that made you lose the fluid in your first transmission?

Who is the guy that is importing and selling new ZF-6 transmissions? That may be a handy bit of info to have.

 

Agreed. For me it's much easier that way. Weather you choose to overfill or not.

x2

 

X-3 about sharing the source of 'new' ZF's. I cannot even get ZF to return my calls (not that I tried all that hard, but I did try).


Toward extra fluid, I did look into a PTO cooler a few years ago (which also allegedly increased capacity), but could not find anybody that explicitly stated there was one that mated to the ZF.

 

Sorry I haven't answered but I haven't had time to look at the thread. I will dig up the paperwork and post the website within a few days.

Chris, no we never did exactly find the source of the loss of fluid, that's the reason that I posted my experience, as a cautionary tale. Some said evaporation, others said a small leak that went unnoticed.

Another thought was that I could have been borderline on the fluid level and I just don't know what happened.

 

Instead of looking for the paperwork, I Googled "new zf6 transmission" and found the place. Joe's transmission New Ford ZF 6 Speed Transmission S6 650 7 3L | eBay *joes_transmission_service* He has a new ZF6 for $2995.00 Joe's Transmission and Differential Service 724-284-0031 , He also sells FORD 7.3 F SERIES DIESEL ZF 6 SPEED REMANUFACTURED TRANSMISSION for
US $1,525.00 Anyone interested can check his e-bay store or call. with the new transmission he gives a 3 year warranty. New Ford ZF 6 speed Transmission S6-650 7.3L 3 year/Unlimited miles warranty/ 4WD and 2WD available. I hope this might help .

 

Yup... Over the years, joe's transmission and Midwest transmission have become a household name to us handshakers...

 

I bought my new one from Joe's. There's some pics of it in my thread.

https://www.ford-trucks.com/forums/1...ot-good-4.html