This is along the lines of what I was thinking - I bought some GL-5 made by
Texico - it says it is compatible with GL-3, GL-4 and MIL-2105 specs.  2105
and GL-4 is what I see on most of my repair manuals so I bought it... but,
I think there are LOTS of trannies out there with GL-5 in there - heck the
VW dealer installed GL-5 in my Syncro!

At 08:57 AM 01/09/2000 -0500, k1cajun wrote:
>David Marshall wrote:
>>
>> ... there is a small privately owned bulk
>> oil agent here in town and they had a 25L bucket of GL-5 that was GL-4 and
>> GL-3 compatible made by Texico for $32.95 CAD... just passing on the tid
>> bit for other people in the need!
>>
>
>You might want to read what Pennzoil has on their website
>http://www.pennzoil.com under Frequently Asked Questions (question #2).
>There seems to be a problem with their HTML code that makes this page
>not display properly for me at home and at work.  I get a blank screen,
>but then I use Netscape's 'View - Page Source' menu to see the HTML code
>where you can read this:
>
>===== Beginning of cut & pasted Penzoil text =====
>2. What happens if API GL-5 gear oil is used in an API GL-4 gear oil
>application?
>
> API GL-4 and API GL-5 products typically use the same extreme pressure
>(EP) additive system, with the API GL-5 having about twice the
>concentration of a API GL-4.  In service, these additives become active
>under extreme load and temperature when the protective oil film can be
>squeezed away.  EP additives work by forming wear-resistant compounds
>with the metal of the gear tooth surface.  As the gears mesh, these
>compounds shield the gear teeth from direct metal-to-metal contact that
>would cause wear and damage to the gears.  If too little of the active
>additive is present, proper protection would be compromised.  Too much
>of this additive could cause excessive chemical corrosion of the gear
>surface.  If an API GL-5 gear oil is used in a application where API
>GL-4 gear oil is called for, chemical corrosion of "yellow metal"
>components may occur, such as bronze synchronizers, brass bushings,
>etc.  This may lead to shifting difficulties or shortened equipment
>life.
>===== Ending of cut & pasted Penzoil text =====
>
>So they say that double the additive makes the lube GL-5.  But it still
>has the required amount that defines lube as GL-4.  So it leads to a
>definition problem.  Is it still GL-4 ?  Some manufactures will define
>GL-5 as also meeting the specs for GL-4 since the definition apparently
>does not say what the upper limit is.  But Pennzoil doesn't see it that
>way and does not consider GL-5 as being GL-4 at the same time.  I've had
>discussions with someone at another discussion board who says his
>sources, including a chemist, says it's OK to use GL-5 and that it's an
>old wives tale that it will hurt your tranny.  He admitted that Pennzoil
>might be right.
>
>So keep this in mind.  It's all up to who do we believe.  Some
>manufacturers and FLAPS may simply be trying to shave production and
>inventory costs by providing only one product.  If the damage is done
>over the long haul, it's hard to pin anything on them.
>
>

-- David Marshall - Volkswagen Enthusiast - Quesnel, BC, Canada   --
-- 78 VW Rabbit, 80 VW Iltis, 80 VW Caddy, 84 VW Westfalia        --
-- 85 VW Cabriolet, 87 Audi 5000 Quattro, 88 VW Syncro Double Cab --
-- David's Volkswagen Home Page        http://www.volkswagen.org  --
-- Fast Forward Autobahn Sport Tuning  http://www.fastforward.ca  --
-- david@volkswagen.org (pmail) or vanagon@volkswagen.org (list)  --