I did a couple of last minute checks today before the cross country and found that my ZF is full of 90wt oil. I thought that it was supposed to have ATF in it? I called the previois owner and he said that it is all he's ever put in it. Will it hurt anything?
Proper fluid in the ZF 5 Speed
- Thread starter DeeseSR
- Start date
The ZF is DEFINITELY supposed to have ATF in it. I would suggest changing the oil out ASAP, and I would start with the cheapest ATF you can get...then run the truck around a little bit (less than 1K miles, then drain it again. This'll help get any residual gear oil out of the tranny.
Gear oil in a ZF can lead to lubrication issues, unless the tranny is already well-worn (in which case it'll make the tranny quieter, and who cares about wearing it more?
). Some people have tried 30 weight engine oil in the tranny to reduce the amount of gear rollover noise...but I do'nt know how well that's worked out as a long-term solution.
Just my $.02...good luck!!
Gear oil in a ZF can lead to lubrication issues, unless the tranny is already well-worn (in which case it'll make the tranny quieter, and who cares about wearing it more?
). Some people have tried 30 weight engine oil in the tranny to reduce the amount of gear rollover noise...but I do'nt know how well that's worked out as a long-term solution. Just my $.02...good luck!!
i forgot where i read this.the zf behind a gasser get regular ATF and the zf behind a diesel is supposed to get synthetic ATF.
Any chance of you finding where you read that? I've never heard that before...although I think synthetic ATF is a good idea (after cleaning the gear oil out, at least), I didn't think anyone was requiring synthetic oil in anything until the mid to late '90's...94f450sd said:
Not doubting you; just like having sources whenever possible
i will try to find it.i cant remember where i read it though.i found it somewhere after i did a clutch in a 89 superduty.if i find it ill let you know.might take a day or 2 though
No rush...thanks for taking the time! 
NJKen
is a daddy!
ZF transmissions used behind diesels after 96 or 97 require synthetic Mercon V or some Castrol product that I can never find. I have installed quite a few remans that have this info all over the trans. I am surprised you can even shift that thing with gear oil in it. I might consider leaving it alone. If it has had gear oil in it all its life its probably wore out pretty good. It is also possible that the gear oil was put in to "fix" a problem.
If everything works OK just leave it be in my opinion. Putting in thin oil might make a big problem.
Best of Luck
Ken
If everything works OK just leave it be in my opinion. Putting in thin oil might make a big problem.
Best of Luck
Ken
I'n with ken on this one. You have a long trip ahead of you and find out why they put in gear oil midway into your trip is not a good thing. I found gear oil in my ZF in my '92 too and did the ATF flush. Found out the bearings is just a "little" noisy..... 
I know a trans rebuild in in the works before I head back out to TX again....
I know a trans rebuild in in the works before I head back out to TX again....
ttman4
Last Nite's Dream..
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Yeah, I been running 50 wt detergent motor oil (not multi viscosity oil) in my '90 ZF for about 5 years now. Mine is a hi miler (at least a gizillion) though & was getting some noise up thru the stick, especially in low RPM's mostly, say when slowing down to make a turn or something. Give it a little fuel & it would go gggrruupppp up thru the stick. Makes it a bit hard to shift till she warms up though, down around 20 deg & especially 20-30 deg below! I shift slow & easy & try to just putt along slowly up thru the gears, as well as not put it in any hard pull for 3-5 miles till warmed up.towcat said:I found gear oil in my ZF in my '92 too and did the ATF flush. Found out the bearings is just a "little" noisy.....
Few years back I ran 30 wt in a sloppy, wore out Turbo 400 auto. in a junky work 1ton. The Turbo 400 was the best part on the truck, & it was slipping & about gone, but then I put over 50K miles with 30 wt.
I've always kept the oil changed, depending how hard I been working it....oil's cheap! Last year I added about 1/2 pt Power Punch...slick things up some.
As you say, I know I got a rebuild coming up, but waiting round for a "roundtoit" as well as I'm looking for a different style tranny. I need different gearing....more low end.
Actually, from what I've learned, some of the gears in the older ZF aren't designed to lube very well with some of these heavier oils. The materials the gears are made out of require ATF for better lube. What I been told anyway.
Just my $.02
James
NJKen said:
see i knew i read it somewhere.but still cant figure out where it was though.
tommyp
Registered User
I was told to run syn 30w in mine with the solid flywheel. sounds good
Mine had some kind of test oil in it. Stickers all over the case said to call an 800 # from some college in N.West somewhere. The fill and drain plugs were epoxied in, so I had to fill it through the shifter and drain it through the pto cover. I called the number but it didn't work anymore, so I can't even find out what the study was about. The oil was brown and looked like the stuff they run in NV3500's in the older S-10's. I refilled it with Syth ATF and now it hates to shift. But at least it works and a rebuild kit isn't all that much. When the DualMass Flywheel bites it, I have my work cut out for me.
here's the definitive guide to ZF lube requirements.......(POKE HERE) when you are done reading this you should be throughly confused then.
JimmyDee
Full Access Member
I'll add my 2 cents here. Had a conversation with a lube engineer about what to use in a standard tranny. The problem, other than shifting when cold, with using gear lube (75w90 etc.) is the sulfur content is high in this type of oil. It creates a good lubrication benefit but when the tranny temp gets over 225° F, it starts working on the sinc gears and parts that are made of brass. A regular engine oil is recommended above using gear lube.
A lot of hot shotters use something thicker that AFT with no problems. I have read where some also use a blend of engine oil and AFT. They seem to feel their trannys last longer using a heaver oil. I really don't know either way but I know I would definitely be using synthetic if I had a manual. I use it in my automatic.
Jim
A lot of hot shotters use something thicker that AFT with no problems. I have read where some also use a blend of engine oil and AFT. They seem to feel their trannys last longer using a heaver oil. I really don't know either way but I know I would definitely be using synthetic if I had a manual. I use it in my automatic.
Jim
