Best manual transmission fluid to keep synchros happy for fast shifting?

[thefleshrocket]

My '15 S4 has 48K miles on it, and has a 1500-miles-on it Ringer Racing Stage 4 clutch with aluminum flywheel, and I've installed the clutch delay valve delete line. Prior to the new clutch, I had to shift slower and more deliberately because the stock clutch would slip if I shifted quickly (even after the CDV delete line). Slower and more deliberately as in, depress clutch pedal, tiny delay, shift, tiny delay, release clutch pedal, tiny delay, mash throttle. After the new clutch, I could shift much more quickly without slippage, but found myself occasionally getting a slight grind on second gear or third gear during a clutch-fully-depressed-but-shifting-as-fast-as-I-can shift. I figured it was time for new trans fluid.

I'd tried Redline MTL (75W80 GL4) in my '02 911's transaxle for about 50 miles to see how it would affect shift feel (it was better than the OEM Porsche fluid but still had a bit of room for improvement.. and I realized that the 911 calls for GL5 due to its hypoid gears), and drained it to replace it with Redline 75W140NS (which is GL5, and does feel slightly better in the 911 than the MTL did). Since the S4's 6MT calls for a GL4, I took the 3 quarts of 75W80 that I'd drained from the 911, along with 1 leftover quart of 75W140NS and put in. Before doing so, I confirmed with Redline that it was safe to mix the two fluids, and confirmed that the GL5 75W140NS was safe for synchros despite being a GL5.

After the fluid change, the transmission feels about the same, and I can still occasionally beat out the synchros. Since it's not just one gear, and since it only happens during very-fast-high-RPM shifts, I'm inclined to think that it's not failing synchros, and that I either need to slow down my right hand, or get "better" fluid. Those of you who're quick shifters, what fluid have you used with good results?

[jcollins28]

I like Motul myself. Seems like it is a popular option on here is as well. I run all Motul fluids in my car. Helps that I get a nice discount too.

[B4Audi]

Factory

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[BrokeBichB8]

Was that 75-140 fluid much more viscous?? I follow your logic of using a heavier oil and expecting it to be more smooth but am unfamiliar with that fluid. From the numbers though Im surprised you don’t have a better trans feel.

I’m subscribed as I intend to swap my fluid for an 80w as southern California has a bit more heat and less cold weather trans requirement.

[thefleshrocket]

I like Motul myself. Seems like it is a popular option on here is as well. I run all Motul fluids in my car. Helps that I get a nice discount too.

Which Motul fluid are you using? Are you able to rip off fast shifts with no grinding?

These are the two that the Motul website says will work for the S4. Not sure what the difference is.
https://www.motul.com/us/en-US/products/gear-300-75w90
https://www.motul.com/us/en-US/products/motylgear-75w90

[thefleshrocket]

Was that 75-140 fluid much more viscous?? I follow your logic of using a heavier oil and expecting it to be more smooth but am unfamiliar with that fluid. From the numbers though Im surprised you don’t have a better trans feel.
I’m subscribed as I intend to swap my fluid for an 80w as southern California has a bit more heat and less cold weather trans requirement.

The rep at Red Line steered me towards the MTL 75W80.. said Audi specifies a relatively thin fluid for the 0B4 6MT. The trans feels fine during normal driving with the 3 x 75W80 and 1 x 75W140NS mix. He said that should result in a 75W85 viscosity rating. Still trying to decide what to do next.

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Factory

Are you able to do fast, grind-free shifts?

[jcollins28]

Which Motul fluid are you using? Are you able to rip off fast shifts with no grinding?

These are the two that the Motul website says will work for the S4. Not sure what the difference is.
https://www.motul.com/us/en-US/products/gear-300-75w90
https://www.motul.com/us/en-US/products/motylgear-75w90

Motylgear is a semi-synth blend, with poorer cold characteristics than Gear 300. If you have deleted your cdv and have a SS clutch line. You should be able to rip off quick shifts.

[B4Audi]

The rep at Red Line steered me towards the MTL 75W80.. said Audi specifies a relatively thin fluid for the 0B4 6MT. The trans feels fine during normal driving with the 3 x 75W80 and 1 x 75W140NS mix. He said that should result in a 75W85 viscosity rating. Still trying to decide what to do next.

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Are you able to do fast, grind-free shifts?

I had redline in before from the previous owner and 1st to 2nd I had to baby it so I switched to factory and it's smooth and I can row through gears as fast as I can.

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[thefleshrocket]

I had redline in before from the previous owner and 1st to 2nd I had to baby it so I switched to factory and it's smooth and I can row through gears as fast as I can.

Holy crap, the OEM stuff is $29/quart, before shipping!
https://www.ecstuning.com/b-genuine-...ter/g052911a2/

I'd bought the $35/quart OEM Porsche stuff for my '02 911's gearbox trying to address a rubbery third gear synchro (and it was decent), but the Red Line 75W140NS was actually a bit better. So I'm a bit hesitant to spend that kind of money on the VAG factory fluid but.. maybe I will.

The part number at ECS is G052911A2. Googling for that returns some $30+/quart stuff, but also Febi Bilstein 75W80 fluid with the same part number for about $12-$15/quart. Is this a case of VAG rebranding the Febi Bilstein stuff with 100% markup?
https://www.pelicanparts.com/More_In...0aAkNwEALw_wcB

https://www.autohausaz.com/pn/FB-G05...YaAoniEALw_wcB

[B4Audi]

Holy crap, the OEM stuff is $29/quart, before shipping!
https://www.ecstuning.com/b-genuine-...ter/g052911a2/

I'd bought the $35/quart OEM Porsche stuff for my '02 911's gearbox trying to address a rubbery third gear synchro (and it was decent), but the Red Line 75W140NS was actually a bit better. So I'm a bit hesitant to spend that kind of money on the VAG factory fluid but.. maybe I will.

Ecs has free shipping

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[BlackJon]

I have a 2013 S4 6MT running IE E40 Throttle body tune with crackles with a stage 3 clutch and flywheel but I don't know when I should change my transmission fluids or how often?
Side note.. when the shop installed my clutch and flywheel, Should I assume that they also changed my transmission fluids too or that's something done differently?

Drive It Like You Stole It

[MATT0404]

Googling for that returns some $30+/quart stuff, but also Febi Bilstein 75W80 fluid with the same part number for about $12-$15/quart. Is this a case of VAG rebranding the Febi Bilstein stuff with 100% markup?
https://www.pelicanparts.com/More_In...0aAkNwEALw_wcB

https://www.autohausaz.com/pn/FB-G05...YaAoniEALw_wcB

Also curious if anyone knows the difference between the Audi branded oil and the Febi oil linked above? Getting ready to order supplies for some PM and trans fluid is on the list.

[thefleshrocket]

Also curious if anyone knows the difference between the Audi branded oil and the Febi oil linked above? Getting ready to order supplies for some PM and trans fluid is on the list.

The AutohausAZ link I posted above is actually mineral-oil based. There's another version that's a couple bucks more which is synthetic: https://www.autohausaz.com/pn/FB-83222339221

[thefleshrocket]

To clarify, we have part number G052911A2 which appears to be the 75W80 GL5 VAG-specified factory fluid for the 0B4 transmission. It's ~$30/quart. https://www.ecstuning.com/b-genuine-...ter/g052911a2/

Google also shows that part number G052911A2 is a Febi Bilstein 75W80 GL5, which appears to be mineral based. (I found a site while Googling that linked to the MSDS for the oil and stated that it was mineral-based, but the link to the MSDS was broken so I couldn't confirm.) There is an associated part number of 40580. This stuff is ~$12/quart. https://www.autohausaz.com/pn/FB-G052911A2

Also under part number 40580 is part number 83222339221, which is also a Febi Bilstein 75W80 GL5, which specifies that it is synthetic, according to thess listing on AutohausAZ and Pelican Parts. It is ~$14/quart.
https://www.autohausaz.com/pn/FB-83222339221
https://www.pelicanparts.com/More_In...-2-339-221-M36

Further Googling for part number 83222339221 shows that the same part number is used by BMW for 75W90 GL4, but that appears to be unrelated to the Febi Bilstein stuff. Interestingly, in this link, the picture of the product says 75W90 but the description says 75W80. https://www.znmperformance.com/bmw-7...w-83222339221/

So, the VAG fluid and the FB mineral-oil fluid have the same part number. Does that mean that FB is the OEM for the VAG fluid? And, therefore, that the VAG fluid is mineral-oil-based, not synthetic? I sent a message to FB on its contact page.. we'll see what I hear back.

[thefleshrocket]

When I searched on Febi Bilstein's website, no matter which part number I used, it all linked to the same page, which doesn't specify synthetic or mineral oil based. https://partsfinder.bilsteingroup.co...0580?make=Audi

On Pelicanparts.com, there are four hits for 40580, three of which appear to be BMW spec, and one which says it's for my S4.
https://www.pelicanparts.com/cgi-bin...cription=40580
Each one has a different ECS part number, though, but all of them reference 40580 in their descriptions.

ECS's page for 40580 claims that it is fully synthetic. https://www.ecstuning.com/b-febi-par...l/g052911~feb/

When you search for the VAG part number G052911A2, FCP Euro has a link to Febi Bilstein 40580, indicating that FB is the OEM for the VM fluid.
https://www.fcpeuro.com/products/vw-...e-vw-g052911a2

I've emailed Febi Bilstein asking for clarification.

[thefleshrocket]

Searching for alternative fluids, I checked Ravenol. It offers a couple of 75W80 choices, but when I searched by the G052911A2 specification, it returned the RAVENOL VSG SAE 75W90. Ravenol part number J1C1109.
https://www.ravenol.de/en/product-ra...sg-sae-75w-90/

But just to be thorough, I browsed through some of the other manual transmission fluids listed.
https://www.ravenolamerica.com/categ...ssion-mtf.html

There's a 75W80 MTF-2 fluid that, if you scroll down into the description, also states that it meets G052911A2. It's a GL4, not a GL5, like the Audi OEM fluid or the Ravenol 75W90. Ravenol part number J1C1002.
https://www.ravenolamerica.com/passe...ravenol-mtf-2/

I checked all of the rest of the Ravenol manual transmission fluids, and none of them list G052911A2. So basically it's the 75W90 GL5 or the 75W80 GL4. Since the 75W80 GL4 matches the Audi OEM spec of 75W80, albeit a GL4 not a GL5, I'm more inclined to go that route instead of the 75W90.

[BucDan]

I have a 2013 S4 6MT running IE E40 Throttle body tune with crackles with a stage 3 clutch and flywheel but I don't know when I should change my transmission fluids or how often?
Side note.. when the shop installed my clutch and flywheel, Should I assume that they also changed my transmission fluids too or that's something done differently?

Drive It Like You Stole It

From my personal experience in other branded cars (Honda and Toyota), OEM transmission oil has always been best, smoothest of them all. Tried Redline and wasn't too impressed with it. Never tried Motul.

I change it every 35K miles. Probably a bit excessive, but it's easy to do. Got my car with 32.5K miles on, and yes I changed it at 35K.

[BlackJon]

From my personal experience in other branded cars (Honda and Toyota), OEM transmission oil has always been best, smoothest of them all. Tried Redline and wasn't too impressed with it. Never tried Motul.

I change it every 35K miles. Probably a bit excessive, but it's easy to do. Got my car with 32.5K miles on, and yes I changed it at 35K.

Thanks so much

Drive It Like You Stole It

[thefleshrocket]

I heard back from Febi Bilstein, and their rep confirmed that 40580 is mineral-oil based, not synthetic.

[jcollins28]

I heard back from Febi Bilstein, and their rep confirmed that 40580 is mineral-oil based, not synthetic.

LOL, you guys are overcomplicating this. Go buy Motul Gear 300 and never look back.

[thefleshrocket]

LOL, you guys are overcomplicating this. Go buy Motul Gear 300 and never look back.

Maybe so, but I am hesitant since it's a 75W90 not a 75W80.

[jcollins28]

Maybe so, but I am hesitant since it's a 75W90 not a 75W80.

Every Audi/VW trans I have seen has always used 75W-90. Including probably every 6MT owner on this board.

[thefleshrocket]

I did the Ravenol 75W80 MTF2. https://www.ravenolamerica.com/passe...ravenol-mtf-2/

It's a bit better, but I can still get a little bit of grind during my fastest shifts into second or third gear at redline. If I slow it down just a hair, it's smooth.

Been doing some more Googling, apparently this is not an uncommon issue during fast shifts, especially with a short shifter, which my car has. I'll just dial it back and live with it, I think.

[ModItNow]

I just got my clutch replaced at jhm and had the fluid changed as well. They put in Motul 300 75w90. Same for rear diff fyi.

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[thefleshrocket]

I just got my clutch replaced at jhm and had the fluid changed as well. They put in Motul 300 75w90. Same for rear diff fyi.

How's it shift? Can you racecar it with no grinding?

[ModItNow]

Yes it's smooth. Just like it was before with original oem oil so I don't know but just to clarify besides the 3R & flywheel I have JHM shift linkage, ECS SS, JBX shifter plate and a BFI knob. I'm at 86k miles.

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[s4sprint]

Just want to add another datapoint. I drive a 2011 S4 6 speed with sport diff. I changed the factory trans oil at 50000 miles to RedLine 70w80 GL4 MTL. I know its good oil but I still have a sense that the synchros do not slow fast enough for shifts into 2nd and 3rd gears. Depending on temperature of the oil sometimes no concern and sometimes I need to shift a little slower to avoid the resistance. No grinding but its not quite as smooth as it could/should be. Its been a year since I put the Redline in. Does it make sense to next time use a more viscous oil?