GM Synchromesh Gear Oil in S4 6-Speed Manual or Other?

[djmika]

Hey All,

I had a 00 A4 before purchasing my 05 S4 a few weeks ago. I have the 6-speed manual gearbox and I'm wondering if the GM Synchromesh gear oil would work as well in this gear box as it did in the 5-speed box in my A4. I know they're entirely different but I tried both Redline and Synchromesh in my old tranny and the GM stuff was 100% better at smoothing out shifts and reducing grinding and notchy shifting.

I don't need an oil change so I won't do it unless there's a way to further smooth shifting.

Thanks...

[zachf88]

bump, I would like to know as well. I hear GM makes great synchromesh (a lot better than royal purple). Doesn't the trans. share oil with the front diff so would synchromesh be ok in this application?

[djmika]

I can't believe no one would know about this... Synchromesh was WIDELY used by the A4 crowd.

[2PUTT]

i used it on my old car. it was really good. if it is GL-4, then you should be good to go.

[ieatfishburitos]

It's good stuff, but make sure the rating is ok like 2putt said.

[zachf88]

I don't think it is GL4.

[dparm]

If it is GL4, you'll be good to go. You cannot use GL5 in the center diff/manual tranny.

[crew219]

Synchromesh is too light. You need a heavier 75w90 spec transmission fluid for the S4 (esp since it shares the fluid with the front and center diffs).

I've had great results from Motul Gear 300.

The transmission actually requires what they call a GL-4+ transmission fluid (GL-5 protection but with the lower corrosion aspects of a GL-4 fluid). By using synchromesh, you'll see significant shearing of the lightweight oil and increased diff and tranny wear.

Dave

[djmika]

Thanks Dave. That clears it up!

[djmika]

Anyone know how much oil the is necessary?

[zachf88]

If it is GL4, you'll be good to go. You cannot use GL5 in the center diff/manual tranny.

Why can't you run GL5?

[fructus]

Here's some info:

Most differential and Manual Transmission oils contain sulfur-phosphorous EP packages. GL4-rated oils contain about 40% to 60% of that amount; the other difference is the Friction Modifier.

Both differential and manual transmission fluids use chemical compounds that subdue or inhibit the corrosive effects of sulfur such as calcium, magnesium, boron, potassium or other basic compounds. Emulsifiers, corrosion and rust inhibitors also are included to do their respective jobs.

Differential lubes use friction modifiers to reduce mechanical and fluid friction and add some anti-shudder friction modifier for limited slip, both very different chemical compounds.

Manual Transmission fluids use a different friction modifier specifically designed for synchro engagement, a modifier that does NOT contain the same chemical compounds as do differential lubes.

Both lubes generally contain the same TYPE EP additives, just in different strengths or additive ratios.

Most manual transmission "specific" fluids (GL4) contain about 40% to 60% of the EP additive of differential lubes (GL5) with inactive or buffered sulphurs. GL4 has come to infer a gear lube with the above percentages of EP additive. The exception of course is ATF fluid used in some of the newer transmissions.

You also have to consider the viscosity of the fluid that the transmission was designed for. The spectrum now ranges from ATF to 75W90 viscosities.

Ever since the synchromesh-type fluids appeared on the scene (such as the GM Synchromesh fluid), drivers have had better shifting due to better synchro engagement, attributed to the specialized friction modifier used in these lubes. This specialized friction modifier is better for metallic and composite synchros in terms of shifting and life.

A diffy 75W90 (GL5) usually has a higher viscosity than does an mtl in the same advertized weight.

GL4 does NOT refer to any specific viscosity, but it refers to a level of AW/EP protection for the gearing and bearings in a transmission.

A synchromesh GL4 Manual Transmission Lubricant (MTL) can be any viscosity from 7.0 cSt (ATF equivalent viscosity) to a 75W90 type viscosity of approx. 14.5 cSt, and contains special friction modification additives for synchronizer assembly engagement.

A synchromesh fluid usually refers to a specialized fluid that contains special friction modification additives for transmissions that use mechanical synchronizer assemblies; those synchronizer assemblies may be made of carbon fiber composites, sintered metal, brass/bronze, or steel-steel materials.

Current MTL GL4 viscosites are:

1. ATF Series - Type; 6.5 to 8.5 cSt (Equivalent ATF viscosity; Note: ATF additive package is weak compared to most GL 4's)
2. Synchromesh Series -Type; 9.3 - 9.5 cSt (such as Amsoils MTF, Texaco's MTL, Pennzoil's Synchromesh, GM and Chrysler's Synchromesh)
3. 75W85 Series-Type; 9.8 to 11.5 cSt ( Redline's MTL, RP's Synchromax LT, Nissan's MTL, Honda MTL, Castrol Syntorq LT)
4. 75W90 Series-Type; 12.8 to 14.5 cSt (Amsoil's MTG, Redline's MT-90).

[ArthurPE]

this comes directly from AoA, for what it's worth...
I call the normal channels: 'talk to the dealer'
the presidents assistant called and asked if I got a satisfactory answer, I told her, less than helpful, 1 hour I get a call from a tech:
RS4
tranny 3.2 liter 75W90 fully synthetic GL4 or 5, rated for a synchro transmission
diff 0.9 liter 75W90 fully synthetic GL5

a week later this showed up, unsolicited


I think the GL4 stuff came about because older VW trannies had soft 'yellow' metal sunchros and bushings, iirc pre 90, maybe older...
GL% not rated for trannies increase wear on these parts
new trannies are not suspceptable
LubroMoly recomends GL5 for it's superior high load perfromance...

do waht you like, do your own research, I'm just sharing my experience...

[ArthurPE]

this comes directly from AoA, for what it's worth...
I emailed the normal channels: get a polite call with the std answer 'talk to the dealer'
the presidents assistant called and asked if I got a satisfactory answer, I told her, less than helpful, 1 hour I get a call from a tech:
RS4
tranny 3.2 liter 75W90 fully synthetic GL4 or 5, rated for a synchro transmission
diff 0.9 liter 75W90 fully synthetic GL5

a week later this showed up, unsolicited


I think the GL4 stuff came about because older VW trannies had soft 'yellow' metal synchros and bushings, iirc pre 90, maybe older...
GL5 that is not rated for trannie use increases wear on these parts (if rated it will say for transmissions or show a pic of one)
newer trannies are not suspceptable
LubroMoly recomends GL5 for it's superior high load perfromance...

do what you like, do your own research, I'm just sharing my experience...

[zachf88]

actually, Liquimoly recommends gl4+... It's only available in Europe but I got my hands on 4 bottles of it.... Liquimoly said that we can use the GL5 as an alternative to the GL4+

[ArthurPE]

actually, Liquimoly recommends gl4+... It's only available in Europe but I got my hands on 4 bottles of it.... Liquimoly said that we can use the GL5 as an alternative to the GL4+

not in the email I got from them directly
GL5

this is what they told me to use:
http://www.europaparts.com/catalog/p...235/image/573/
http://www.europaparts.com/lubro-mol...l-1-liter.html

notice the pic of a tranny gear pattern, a tranny mntd rear xfer gear set and a rear diff

[zachf88]

This is what LiquiMoly Germany recommends for modern Audis:

http://translate.google.com/translat...n&hl=&ie=UTF-8

[ArthurPE]

This is what LiquiMoly Germany recommends for modern Audis:

http://translate.google.com/translat...n&hl=&ie=UTF-8

their product selector, I looked there too... http://www.liqui-moly.de/liquimoly/w...oil_guide.html
I asked them about that...they said it was superceded and GL5 was the product...
I also asked TorSen, the f to r diff, they also said GL5
I also emailed getrag, never got an answer

it's confusing, I'll be using oem

[zachf88]

no kidding..... I'm running GL5 right now and it's nice, but its knotchy from time to time..... I'll be getting GL4+ in there soon!

I did run Royal Purple Synchromax and it was as smooth as butter, but it wore down pretty fast

[ArthurPE]

I'm running LubroMoly fully synthetic 75W90 GL5, about 1k miles, I'm putting the oem stuff in, hopefully tomorrow
it's TOO slippery, pops out of 3rd, but never under load...
it feels much thinner than oem, very smooth and easy to engage
oem was thicker, and you had to be more deliberate, but it felt 'heavy duty', not sure how to explain it, lol
the Lubro is much quieter, less gear whine, but honestly, I LIKED the gear whine, lol

GL5 is fine for the rear diff, but since I have the oem stuff, it's going in too

[alvinaus]

Hey ArthurPE
Could you take a picture of the labels of the oil you got from Audi, or share the part number/oil specs on the label?

[ArthurPE]

just did mine...put the oem in
front took a bit less than 3 liter, maybe 2.9...
I let it drain for 1/2 hr, no drip left...
filled to drip, let stop, squeeze bulbed a bit out ~1mm below lip...

diff took a little over 1, but spilled a bit, maybe 1.2 liter actual
same drain & fill as above...

I have 3+ tranny and 1.5+ diff left, enough for another change...