[DeTomaso] Gear Oil

Fri Sep 29 11:06:21 EDT 2017

http://panteraparts.com/techTips.php

Now that Castrol has discontinued the long recommended 80W90 Hypoy GL-4
gear oil, Now what oil do we use in our Pantera Transaxles and why?
There are many discussions about what is the proper oil to use in the
Pantera ZF 5DS-25/2 transaxle. Basically today there are 2 oils, a Castrol
80W90 LS (Limited Slip) and the Redline 75/90 NS, available from Pantera
Parts Connection (1-800-DeTomaso (338-6627)) now, so which should we
choose?

The answer is complicated because The ZF gearbox is not just a simple
Transmission Gear only type design so a lubricant does indeed need to
satisfy the requirements of a limited slip differential ... plus the ring
and pinion gears, bearings of all types, transmission gears and the
synchronizer rings. The lubricant must also be non-corrosive to steel,
aluminum, and "yellow' metals (i.e. copper, brass or bronze) especially if
your ZF has these brass synchro rings.ZF's recommended viscosity was SAE
80 n 1972 or SAE 80W90 stated in today's modern lubricant technology. The
synchronizers, brass/bronze parts and limited slip differential within the
gearbox has traditionally meant lubricants rated API GL-4 are the best
lubricants for the ZF. GL-4 lubricants are medium load lubricants in which
the additive package has been specifically formulated to meet the
requirements of limited slip differentials and synchronizer rings, while
being non-corrosive to aluminum and yellow metals. API GL-4 lubricants
were common lubricants for transmissions and transaxles. The Castrol 80W90
Hypoy Gear Oil (GL-4) was among the most favored lubricants ZF originally
recommended to Ford but Castrol has now discontinued this GL-4 grade since
2008. Now what?

RBT states that they recommend that you use an API GL-4 rated gear oil.
The RBT/ZF transaxle designs use the highly efficient Spiral Bevel style
crown wheel and pinion set. There is no Hypoid offset in this type of
gearing; hence, there is no longitudinal sliding along the face width of
the tooth. Therefore, the additional friction modifiers used in GL-5 type
oils are not required. These friction modifiers, required to reduce heat
and prevent scoring on Hypoid gear sets, can have an adverse effect on the
function of the transaxle synchronizers, for example, requiring greater
shift effort. But all the oils available today are GL-5 rated so they need
to be specially blended and balanced with friction modifiers.

Today if you have Brass Syncro Rings installed in your ZF we must
recommend to put you into a newer formulation Friction Modified Synthetic
like a RedLine 75W90 NS GL-5 LS, available from the Pantera Parts
Connection, for use in differentials with the Spiral Bevel style crown
wheel and pinion set found in the ZF or RBT Transaxle. This oil is
designed to help slow synchro's for easier shifting across a broad
temperature range. It contains the extra pressure additives, but lacks
friction modifiers to balance slipperiness. This oil incorporates low
sulfur content for Improved copper corrosion protection to prolong synchro
life. This Synthetic oil helps with Limited Slip lock up and can be
additionally tuned with Redline limited slip Friction Modifier if limited
slip clutch chatter becomes evident.

Standard GL-5 lubricants found in most auto parts stores have a higher
load rating than GL-4 lubricants, but the GL-5 additive package is usually
not compatible with limited slip differentials or Brass synchronizer
rings; the GL-5 additive package is usually corrosive to other yellow
metals too. However, some API GL-5 lubricants contain friction modifying
additives specifically added for limited slip differential usage (the
label should specify it has a modified API rating such as GL-5+ or
GL-5-LS). API GL-5 lubricants are common lubricants for axles that are
independent from the transmission. Even when modified for limited slip
differentials GL-5 lubricants are not usually considered suitable for the
synchronizer rings & yellow metals in a transmission or transaxle. So use
of these standard GL-5 oils is not recommended for long term use.

However, in the case of Castrol's current non synthetic 80W90 Hypoy Gear
Oil (which is rated API GL-5 LS) available from Pantera Parts Connection,
which has been Transaxle builder RBT's favored recommendation which
indicates to me it must be OK for the ZF's for half the cost of the
Redline synthetic oil, at least when using the RBT Cast Iron Synchro's
that RBT Sells and uses in their ZF/RBT rebuilds. Beware because ZF also
produces Brass Synchro's for the ZF-5DS-25/2 that some rebuilders use that
are less expensive and will work fine as long as you use the Synthetic
Redline oil described above.
That is why every question is answered and qualified with another
question. How fast do you want to go, and for how long?
 Larry Stock

On 9/28/17, 8:11 PM, "DeTomaso on behalf of Mike Drew via DeTomaso"
<detomaso-bounces at server.detomasolist.com on behalf of
detomaso at server.detomasolist.com> wrote:

>Don,
>
>He's not asking about Panteras specifically, but rather a general
>question about other cars.
>
>And with respect to your recommendation, the Pantera owners manual
>clearly specifies the use of GL-5, not GL-4. I think the ZF manual says
>the same thing. 
>
>I once put GL-4 in my gearbox by mistake and ran it for a couple of years
>before realizing it. I switched it out for the proper oil and didn't
>notice a bit of difference.
>
>Mike
>
>Sent from my iPad
>
>> On Sep 28, 2017, at 21:45, Don Thomas <dtpantera at gmail.com> wrote:
>> 
>>   Use a GL-4 rated transaxle oil.
>>   I use this:
>>   
>>[1]https://www.amsoil.com/shop/by-product/transmission-fluid/manual/man
>>   ual-transmission-and-transaxle-gear-lube-75w-90/?code=MTGQT-EA
>>   Enjoy.
>>   -dt
>>   On Thu, Sep 28, 2017 at 6:31 PM, Paul Timko <[2]thedrol at pobox.com>
>>   wrote:
>> 
>>     Can someone explain the difference between Gear Oil for limited slip
>>     differentials and standard gear oil?
>>     I'm not looking for a ZF oil recommendation, just some general
>>     knowledge that I can apply to all my cars.
>>     Paul
>>     #9270
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>> References
>> 
>>   1. 
>>https://www.amsoil.com/shop/by-product/transmission-fluid/manual/manual-t
>>ransmission-and-transaxle-gear-lube-75w-90/?code=MTGQT-EA
>>   2. mailto:thedrol at pobox.com
>>   3. mailto:DeTomaso at server.detomasolist.com
>>   4. http://server.detomasolist.com/mailman/listinfo/detomaso
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