ZF Dash 2 Transaxle Gear Lube

Thanks for the tip. Because I really wanted a pure GL-4 gear oil, I went with Pennzoil's synthetic 75W/90 gear oil. My car shifts perfectly, especially cold, and so far no leaks. The only down side is I could not find it locally and had to buy case at $20.00 a quart. Here is a link to the vendor I ordered from and the technical specs. http://www.mil-specproducts.co...SYNTHETIC-75W90-GL-4

Brad Penn makes a gear oil that sounds like it's perfect for our transaxles. It's called "Multi-Purpose 'Classic' GL-4 SAE 80W-90 Gear Oil". Here's the description: The SAE 80W-90 is specially blended using high quality PENN-GRADE® mineral base stocks and select additive technologies. It is designed to be used with “yellow” metallurgy (brass, bronze, copper) and other ‘soft’ metals used in synchronizers, bushings, thrust washers and other components typically found in classic manual transmissions and transaxles. In applications specifying API GL-4 quality lubricants, use of API GL-5 lubricants with higher extreme pressure additive activity/concentration can damage these ‘soft’ metal components.

That being said, POCA President Les Gray says he's tried them all and Redline 75W90 NS (synthetic) is the best he's ever used in a ZF.

quote:

Originally posted by David_Nunn:
Brad Penn makes a gear oil that sounds like it's perfect for our transaxles. It's called "Multi-Purpose 'Classic' GL-4 SAE 80W-90 Gear Oil". Here's the description: The SAE 80W-90 is specially blended using high quality PENN-GRADE® mineral base stocks and select additive technologies. It is designed to be used with “yellow” metallurgy (brass, bronze, copper) and other ‘soft’ metals used in synchronizers, bushings, thrust washers and other components typically found in classic manual transmissions and transaxles. In applications specifying API GL-4 quality lubricants, use of API GL-5 lubricants with higher extreme pressure additive activity/concentration can damage these ‘soft’ metal components.

That being said, POCA President Les Gray says he's tried them all and Redline 75W90 NS (synthetic) is the best he's ever used in a ZF.

I agree with the synthetic. I would add that the Mobil1 is excellent as well.

The ZF isn't particularly susceptible to developing leaks through the gaskets associated with using full synthetics at all.

The flat gaskets are cork which really is the issue right there. Cork shrinks.

The rear cover has the tendency to want to drip through the stud holes. Sometimes the only way to fix that is to put o-rings on the studs under the nuts.

Other then that it is really problem free.

I would add that the Redline for some strange reason seems to tighten up the feel of the gearbox itself.

It does that in every manual transmission I have tried it in and it does it to every box.

It makes it feel like a new transmission. Tight and precise.

Alchemy I tell you!

Synthetics are always iffy in our 50-year-old ZF design. Some synthetics swell certain synthetic rubbers while others shrink them. The shrinking causes leaks while swelling only softens the sealing parts, but the assembly carries no internal pressure so it seems benign. If you found a synthetic by experiment that doesn't leak, good.
Temperatures inside a ZF under HARD driving do not seem to exceed 180F by my measurements (plus a few racers)- hardly enough to chase out condensation. So 'high-temp' lubes or diff- coolers are not needed this side of the Daytona 24 or LeMans 24.
LSD additives are needed only if your ZF chatters in turns- as the thread-starter here had. Chatter shock-loads all the gears engaged and is best avoided for longevity.
Blending different lubes for any reason is an un-good idea. See this month's POCA Newsletter on the effect of additives in motor oils to 'adjust' ZDDP levels, and what it does to the load-carrying properties of otherwise good oils.
As for metal compatibility with diff lubes, there are no brass/bronze parts in ZFs that I've found; everything is high-alloy steel: the synchos are all-steel as are the few thrust washers and the cases are aluminum.

Just a follow up to my original post. Ive had the Pantera out in several extended drives (1 hour plus), with expressway driving and stop and go cruising (the Woodward Dream Cruise). The car is shifting smoother than ever, there is no posi chatter and I have not added any posi additives.

When I purchased my Pantera, (4384) 2 1/2 years ago it had a fairly average shift.
It also has a slight oil weep from the right side output shaft.
Drained the oil & filled with Redline "lightweight" shock proof gear oil.
Much nicer shift its now very smooth to drive.
And the oil leak has almost disapeared.
So maybe it swelled the seals some?
Only get a tiny drip on real hot days when the engine & transmission are working much harder to stay cool.

regards,
Tony.