[s-cars] Internal fluids - again

Kirby Smith kirby.a.smith at verizon.net
Tue Dec 3 08:31:01 EST 2002

It is my understanding that GL-5 gear oils contain sulfer compounds that
will attack the brass synchros if the oil temperature gets high enough.
High enough is evidently feasible in street-driven cars.  Audi's
specified oil is a GL-4, Redline recommends a GL-4 type.  Not having
changed the synchros in my Audi gearbox, (although I did help do my
Corvair (Saganaw) gearbox a long time ago), I don't know how big a job
it is.  But I suspect, by extension from every other Audi job, it would
not be the preferred way of spending one's time.


Erics Mail wrote:
> This is a multi-part message in MIME format.
> --
> [ Picked text/plain from multipart/alternative ]
> Guys,
> According to my Trannie guy (Builds Race trannies for VW's and Audis) in Winchester California.  Sean from Kraftwerks.  The main diff between GL4 and GL5 is the additives.  GL5 is suggested in all straight gear boxes (Diffs, Gear side of auto trannie, and any gear box that does NOT contain soft metal syncros).  The addititives in the GL5 apparently are too 'Fine' (My word not is, meaning that the particals are too small) and lubricate the syncros incorrectly causing them not to match speeds correctly causing faster breakdown.  GL4 is suggested for all new and recently rebuilt Audi and VW Manual gear boxes because it has different additives that are specially made for soft metal syncros.
> I may not have gotten all the technical terms correct in the above, but the gist of it is, if the syncros are on their way out, go for the GL5, it will make them 'feel like' they work better for a short time, but they will still fail.  If you are not having a problem, Stick with the GL4 (G50), espically if your trannie calls for it.  It will last longer.
> Eric
> Message: 11
> From: "Rich Assarabowski" <konecc at snet.net>
> To: "'Martin, Gary G'" <MartinGG at aetna.com>,
> "'AUDI S Cars Discussion List'" <s-car-list at audifans.com>
> Subject: RE: [s-cars] Internal fluids -  again
> Date: Mon, 2 Dec 2002 21:41:31 -0500
> Gary:
> Did you use BG Synchroshift or Synchroshift II??  From what I gather,
> Synchroshift is a mineral oil and is no longer made, while Synchroshift
> II is fully synthetic.  See http://www.bgprod.com/autodrive.html for
> details.  Unlike the Redline oils (see
> http://www.redlineoil.com/products.htm), BG does not offer very much
> technical or application information on their web site.
> I'd also be interested in the experience of others specifically with the
> S4, I've had very good luck with Redline MT-90 in my 200, I'm looking to
> replace the fluid in my S4 but haven't decided which way to go.
> -- Rich
> >I agree, that is strange. I can't explain it. I'm sure lots of others
> are using MT90 also, but I don't
> >hear a lot of me too, concerning shifting.
> >
> >Gary
> >
> >
> >Gary-
> >Funny that you mention difficulty shifting in cold weather, because my
> car has MT90 in the trans and it
> >shifts just fine. OTOH, the A4 with the factory G50 fill is really
> notchy and hesitant in 28-35F degree
> >weather, making me shift very slowly and deliberately for 2nd and 3rd
> gear.
> >
> >Taka
> >I used Redline MT90 in my S4 tranny, and was experiencing stiff
> shifting for the first few minutes in
> >cold weather. It got to be quite annoying, so I switched to BG
> synchoshift and have no more problems.
> >These are both GL4 spec, and I think that IS an important point,
> although I'll let some oil expert detail >why.  Why did BG recommend
> against it? With tranny warmed up, I'd say both shift equally smooth.
> >
> >Gary
> >
> >
> >Hi all
> >With this colder weather it is time to get to my gear fluids Anybody
> use BG products in their Audi's? I
> >seem to remember a post flaunting BG synchroshift for our transmissions
> Problem is the BG people dont
> >recommend it... They say use their Ultra Guard product which is a 75-90
> GL-5 rated synthetic.  They also >say it can be used in GL-4
> applications. .... Can anybody please confirm:
> >Trans- GL-4 ONLY, 75-90wt, 2.9liters - How important is the ONLY? Diff
> - GL-5, 90wt, 0.8liter. Thanks
> >Aaron
> --
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