ZF Fluid type and quantity

Chuck · 22nd December 2009, 12:29 AM

I know this has been addressed before because I have looked at every thread addressing the subject that I could find. But wanted to get some current feed back to see if the recommendations were still the same.

On an inverted ZF transmission, is the recommended fluid level for a fresh fill 3 quarts? That is what ERA recommends. But have seen references ranging from 2 liters to 2.7 quarts to 3.8 quarts.

I have some Mobile I 75-90 synthetic sitting on the shelf. Acceptable? or is there something better?

Lubricants mentioned include:
1. Mobil I 75-90 synthetic
2. Mild EP oil, SAE 80
3. Penzoil Gearplus 80w-90 GL-5
4. Castrol Hypo C 80W-90

Jack Houpe · 22nd December 2009, 06:55 AM

Chuck, I put 3 quarts of Mobil 1 75-90 in my M1 ZF. I use this in every car I own, the only problem I have ever had is it will find a leak. You can change the oil in a transaxle that has no leaks and in a couple runs with Mobil 1 come back and find one under the car. Maybe just me but its happened 2 other times.

Chuck · 22nd December 2009, 02:45 PM

Thanks Jack. The leak issue is curious. I use synthetic in several of my cars, including the 427 FE Cobra, and had not had a problem with leaks any more than convential oil. But glad to get a vote for the Mobil I, since just happen to have that on the shelf!

Kelly · 22nd December 2009, 06:40 PM

I've heard many complain of leaks after switching form dino lube to syntheics. Some claim that the constituents of the two lubes are soluable to varying degrees in the seal materials and a switch to synthetic after prolonged exposure to organic lube causes slight relaxing of seals after the switch. I have a hard enough time keeping the organic lubes contained.

Kelly

David Briggs · 22nd December 2009, 10:22 PM

I am running Mobil 1 in my ZF it is dry as a bone!

Jack Houpe · 23rd December 2009, 05:07 AM

Quote:

Originally Posted by David Briggs

I am running Mobil 1 in my ZF it is dry as a bone!

David are you sure its not dry as a bone?

The only leak I had in my ZF was the speedo cable which I fixed. But my R5, Countach, and Ferrari all drip some place.

Rob · 23rd December 2009, 01:35 PM

Hi Chuck,
Per Lloyd @ RBT, 3qts with no friction modifier additives was the response when I asked a couple years ago. I used good ole fashioned 80/90 in mine (well.....what was mine... ;-)

Did some google searches... you may find this one of value:
ZF reseal

Chuck · 24th December 2009, 12:21 AM

Looks like two votes for Mobil I.

Rob: Thanks for the info. The article was a bit disheartening. Sounds like the author's ZF leaked like a sieve. Dang.

Looks like three quarts is the magic number.

Wondering if there is any research out there suggesting that synthetics are more inclined to leak than conventional lubricants in a freshly rebuilt tranny. What I have seen thus far appears to be anecdotal.

Rob · 24th December 2009, 10:12 AM

Hey Chuck,
I've heard others also complain about leaks. However, I think if it is put together with care, there should be no issues. I've been told not to use sealer, however I didn't listen to this advise. When the unit was stripped down, I cleaned all the mating surfaces very carefully. Knocked down any irregularities with a flat file. Used brake cleaner to clean the surfaces, and applied a thin film of black RTV to the gaskets. Not a drip.

Regarding the lubrication...... by using Mobile 1 (or any synthetic)... isn't this similar in result to using a friction modifier? In other words, by using a low friction lube, wouldn't you be negatively affecting the performance of the diff. friction plates? Just food for thought/discussion.....

Chuck · 24th December 2009, 11:06 AM

Quote:

Originally Posted by VintageVenom

Hey Chuck,

Regarding the lubrication...... by using Mobile 1 (or any synthetic)... isn't this similar in result to using a friction modifier? In other words, by using a low friction lube, wouldn't you be negatively affecting the performance of the diff. friction plates? Just food for thought/discussion.....

Now that is a good point. I, of course, am clueless. The author of the article you attached re the Panterra ZF rebuild used Castrol Hypo C 80W90 'limited slip' lube. The Castrol web site specifically describes it for use in limited slip diffs. Perhaps that is the way to go. Thanks for the thought.