[DeTomaso] ZF Gear Lube Question

[pantdino at aol.com]

Just my opinion:

One cannot assume that what was called GL5 in 1973 is the same thing being sold today, so that is of questionable validity.
Limited slip diffs are much more common today than in 1973, so GL5 gear oils come with some limited slip additive already in it.
If you can find a bottle of GL5 that says "not for use in limited slip differentials" then that would not apply, but i haven't seen any.

The ZF has basically 2 parts that are separated in a traditional car: the transmission and the differential.

The synchros of the transmission part need some friction between the spinning parts to slow the next gear. Without that friction, they won't work as well and the gears will tend to crunch when they meet.  

So you get to choose what is most important to you, wear on your gears or noise from the limited slip plates (which are probably worn out already anyway). If you get noise from the plates you can add a little limited slip additive until it stops. 

I am usually a cheapskate and don't spend extra money unless it is necessary, but in this case it is a no-brainer for me:  get Red Line 75W90 NS.. The 75 number means it is thinner at lower temps, while the 90 means it does not get too thick at high temps. This is the same kind of stuff that is never changed in some modern cars-- for us it can be left for 5 yrs if you get the transaxle up to temp to burn off water vapor when you drive it. 

Jim Oddie




-----Original Message-----
From: MikeLDrew at aol.com
To: JDeRyke at aol.com; joernco at online.no; detomaso at realbig.com
Sent: Fri, May 28, 2010 7:30 pm
Subject: Re: [DeTomaso] ZF Gear Lube Question



n a message dated 5/28/10 18 45 54, JDeRyke at aol.com writes:

 As to the type, remember the ZF transaxle as a complex and expensive car
 part PREDATES the 'GL' lubrication rating system. 
 
>>Not in our cars, it doesn't--check the manual.

 >Not sure what GL rating
 parameters are and I suspect no one else on this list has found out, 
 either. All
 the ZF factory manual says is to only use 'mild' EP (extreme pressure) 
 gear
 oil, 80W conforming to spec- Mil-L-2105 (A). 
 
 >>>The standard owner's manual is mostly a Gee-Whiz thing, but it does have 
ome valuable information hidden inside it, if one takes the time to look 
or it.   Specifically germane to this discussion, they give very specific 
ecommendations as to quantity and type of gearbox oil to be used.
The blue-covered manual lists the capacity as 7 1/2 U.S. pints, and gives 
he oil type as "SAE 90 - E.P."   The red-covered manual goes into a bit more 
etail; it calls for   SAE 80 AP GL-5 for the USA, and Agip F.1 Rotra MP 
AE 90 for Europe.   (I can't help but wonder if the "SAE 80" thing is a typo, 
nd they really mean SAE 90--probably SAE 80-90 would be the best bet).
It's easy to find suitable gearbox oils in the USA.   For example, here's 
hat Valvoline has on offer:
HP Gear Oil GL-5
    •     Applicable where an API GL-5 gear oil is specified
    •     Available in SAE 90, 80W-90 and 85W-140 and viscosity grades
    •     GL-5 90: MB 235.0, MAN 342-N and ZF 05A/07A/16B/17B approved
Every other gear oil maker (Castrol/Pennzoil/Mobil 1/Amsoil/Brad 
enn/etc./etc./and so forth) offer similar oils with similar characteristics; 
ome are 
ineral-based while others are either a mineral/synthetic blend, or pure 
ynthetic.
Once the basic parameters have been established (you want GL-5, and either 
traight 90-weight, or somethingW-90-weight), it's probably far more 
mportant to maintain the oil by changing it periodically (every 2-3 years) 
ather 
han concentrating so much on the specific brand.
Mike
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