Break in 6MT fluid change

[AC2024]

Hi All,

First post - I am taking delivery of a 2024 CT4-V Blackwing on Wednesday. 6MT, Black on black, with performance seats and alcantara. I am beyond excited. I am joining the seemingly large group of ex-BMW folks who are choosing Blackwings over G80 M3s.

I've been preparing for my break in service and reading the forums, but one thing that seems notably absent is discussion on a fluid change for the 6MT. It's a bit strange to me that the OM recommends a diff fluid change before tracking but mentions nothing of a 6MT fluid change for break in. I am planning to do a 6MT change at 1500 miles along with the diff, but figured I would throw it out there to see anyone had thoughts or opinions. I figure it's easy and cheap, and what's the worst that can happen? Besides, I like being underneath cars almost as much as driving them.

 

[Aaron4BW]

Congrats & welcome to the dark side! I can give you my 2 cents on what I've done, but everybody has their own opinion on this subject. I did an engine oil change at 500, 2500 & 5k. I did my diff fluid at 2k & I have yet to do my trans. Im almost at 7k & looking at what fluid I want to put in my trans. Ive settled on the Tremec fluid because of the thicker viscosity compared to the ATF fluid people use. I waited a little longer to do my trans because I wanted a fair amount of NLS in all gears to get my synchros nice & broken in lol But like I said, everyone has their own opinions & more oil changes sure doesn't hurt anything. Btw I used mobil 1 gold cap 5w30 for the first 3, but switching to 0w40 supercar after next change & used redline 75w85 for the diff. (I'm DP/tuned on 95 oct somewhere in the 5XXs whp)

 

[Jim2000]

Congrats & welcome to the dark side! I can give you my 2 cents on what I've done, but everybody has their own opinion on this subject. I did an engine oil change at 500, 2500 & 5k. I did my diff fluid at 2k & I have yet to do my trans. Im almost at 7k & looking at what fluid I want to put in my trans. Ive settled on the Tremec fluid because of the thicker viscosity compared to the ATF fluid people use. I waited a little longer to do my trans because I wanted a fair amount of NLS in all gears to get my synchros nice & broken in lol But like I said, everyone has their own opinions & more oil changes sure doesn't hurt anything. Btw I used mobil 1 gold cap 5w30 for the first 3, but switching to 0w40 supercar after next change & used redline 75w85 for the diff. (I'm DP/tuned on 95 oct somewhere in the 5XXs whp)

If you have any issues with the transmission, won't GM refuse to repair it at their cost because of a different fluid? Same applies to the differential.

 

[Neveready]

Welcome and congrats! IMO, The service recommendations are for light use non track driving. It’s almost as if they didn’t factor in how the Blackwings are being used.

From what I’ve read on the forums about those who have flushed their trans early they didn’t see any contamination with the factory fluid. I’m a firm believer of flushing fluids early and often, I’d change it if you feel more comfortable. The tremec tr6060 is better than what you’ll find in any modern brand. That being said, several have had transmission issues early on and changing the fluid had little to no improvement. The GM fluid is ok, but Tremec offers better fluid you can use on their website, However, if something happens this could pose a problem with the warranty.

I have read others who flushed their diff fluids early (under 5k) already noticed contamination. I’m changing mine as soon as it’s in stock but I’m at 2500 already with no track time. A week ago they told me the warehouses don’t have any in stock so they are sourcing from a local dealer. I would only recommend OE fluid for the Ediff and warranty claims.

I’d also flush the engine oil sooner rather than later, I wouldn’t wait around till it hits 3k but id consider changing it between 500-1500 miles. I’d stick to supercar recommended oil just for warranty purchases. I had a 22 5BW and did the first flush at 531 and again around 4,279. I ran the second sample and the numbers were very good. My 24 5BW… not as good as I’d hoped supposedly “ok”.

As with any car you track, changing brake fluid before, after or even better both depending on the circumstances is best.

 

[Aaron4BW]

If you have any issues with the transmission, won't GM refuse to repair it at their cost because of a different fluid? Same applies to the differential.

Definitely a possibility, but coming from an X nissan service technician of 10 years, seeing GTRs, 370s & even non performance cars get warrantied, the service tech is not trained in telling what type of fluid is in these things. If it smells like diff fluid & doesn't show signs that it has never been changed, it will pass. Same thing with engine & trans fluid. They look for signs of abuse before anything. Tire wear, clutch wear, brake wear (hot spots) & modifications. They will not do 3rd party oil analysis ever. But, if you feel more comfortable using OEM fluids, then go for it. I just want my drivetrain components to withstand the heat cycles I know I put on them & last far outside of the warranty period. Remember, dealers & manufacturers don't care about anything lasting past the warranty period. Only enough to get through it lol

 

[AC2024]

Congrats & welcome to the dark side! I can give you my 2 cents on what I've done, but everybody has their own opinion on this subject. I did an engine oil change at 500, 2500 & 5k. I did my diff fluid at 2k & I have yet to do my trans. Im almost at 7k & looking at what fluid I want to put in my trans. Ive settled on the Tremec fluid because of the thicker viscosity compared to the ATF fluid people use. I waited a little longer to do my trans because I wanted a fair amount of NLS in all gears to get my synchros nice & broken in lol But like I said, everyone has their own opinions & more oil changes sure doesn't hurt anything. Btw I used mobil 1 gold cap 5w30 for the first 3, but switching to 0w40 supercar after next change & used redline 75w85 for the diff. (I'm DP/tuned on 95 oct somewhere in the 5XXs whp)

Thanks for your reply, but I am confused. Per the service manual 88861800 is specified as the transmission fluid which is a 75W90, not an ATF. On the Tremec website, the 6060 spec sheet lists Dexron III as the fluid - this seems to be the opposite of what you mention above. the OEM 88861800 is like $7 a quart, so I was just planning to do that.

 

[AC2024]

Congrats & welcome to the dark side! I can give you my 2 cents on what I've done, but everybody has their own opinion on this subject. I did an engine oil change at 500, 2500 & 5k. I did my diff fluid at 2k & I have yet to do my trans. Im almost at 7k & looking at what fluid I want to put in my trans. Ive settled on the Tremec fluid because of the thicker viscosity compared to the ATF fluid people use. I waited a little longer to do my trans because I wanted a fair amount of NLS in all gears to get my synchros nice & broken in lol But like I said, everyone has their own opinions & more oil changes sure doesn't hurt anything. Btw I used mobil 1 gold cap 5w30 for the first 3, but switching to 0w40 supercar after next change & used redline 75w85 for the diff. (I'm DP/tuned on 95 oct somewhere in the 5XXs whp)

Yea, I am planning to do exactly the same as you mention for motor oil and the likely stick to ~5K as my normal interval. For the diff and trans, do them at 1500, 10K, and then every 30K. Planning to run castrol edge 5w30. Any reason you you are going 0w40? Unlike other cars, I don't see multiple weights listed in the manual - just the 5w30

 

[Neveready]

I can tell you from experience and speaking to others on the forum in dealing with Transmission issues at a Cadillac dealership, GM corp gets involved more than I expected. In some cases GM has come onsite and disassembled the transmission to determine root cause and damage. If they went through all that, I would not be surprised if they ran an oil sample to ensure it's OE fluid.

Personally, even if money was no object I wouldn't risk using alternative fluid under warranty. I suppose one could use something else and if problems arose they could flush out the alternative fluid twice with OE fluid before having it serviced. So far anyone that's had trans issues it's been a full replacement at the cost of $8-$10k. The quickest I've heard anyone get a trans replacement is 4 weeks but most who have had trans replacements wait 6 to 12 weeks.

An engine replacement is a 5 figure job.

 

[Aaron4BW]

Thanks for your reply, but I am confused. Per the service manual 88861800 is specified as the transmission fluid which is a 75W90, not an ATF. On the Tremec website, the 6060 spec sheet lists Dexron III as the fluid - this seems to be the opposite of what you mention above. the OEM 88861800 is like $7 a quart, so I was just planning to do that.

Dexron 3 is an ATF fluid. In fact most of the ZL1, corvette, etc guys use their favorite kind of synthetic ATF (redline D4, valvoline atf, etc) ... i mean it works so there is nothing wrong with it, i just plan on using the Tremec HP-MTF.

Im going to try 0w40 because I know tapout uses that on their higher hp cars. Probably not totally needed since the oil temps stay very cool, but I wanna use the "supercar" formula.

 

[Neveready]

I noticed this post and it’s an interesting read. Although I haven’t researched this technique fully I would consider it. Again, it’s a risky proposition for warranty work.
Post in thread 'Manual Transmission in cold temps'
Manual Transmission in cold temps

 

[MatthewAMEL]

Hi All,

First post - I am taking delivery of a 2024 CT4-V Blackwing on Wednesday. 6MT, Black on black, with performance seats and alcantara. I am beyond excited. I am joining the seemingly large group of ex-BMW folks who are choosing Blackwings over G80 M3s.

I've been preparing for my break in service and reading the forums, but one thing that seems notably absent is discussion on a fluid change for the 6MT. It's a bit strange to me that the OM recommends a diff fluid change before tracking but mentions nothing of a 6MT fluid change for break in. I am planning to do a 6MT change at 1500 miles along with the diff, but figured I would throw it out there to see anyone had thoughts or opinions. I figure it's easy and cheap, and what's the worst that can happen? Besides, I like being underneath cars almost as much as driving them.

100% not required, but certainly won't hurt. I used to do a -6060 fluid swap at the end of every racing season.

They made it easier on the Blackwing by moving the temp sensor to a different port.

Just be sure to use the GM OEM fluid OR the TREMEC HP-MTF. Don't go into the redline/amsoil, etc trap.

If you use the GM fluid, follow the procedure to the letter, with the expansion properties of the ATF, overfilling the -6060 and getting the fluid hot has caused issues that GM is reluctant to fix.

The HP-MTF is manual fluid and does not have the same issues. If you use the HP-MTF, allow enough fluid for a 'flush and fill'. Gotta get the OEM fluid out of the transmission cooler and lines.

 

[Orange Whip]

100% not required, but certainly won't hurt. I used to do a -6060 fluid swap at the end of every racing season.

They made it easier on the Blackwing by moving the temp sensor to a different port.

Just be sure to use the GM OEM fluid OR the TREMEC HP-MTF. Don't go into the redline/amsoil, etc trap.

If you use the GM fluid, follow the procedure to the letter, with the expansion properties of the ATF, overfilling the -6060 and getting the fluid hot has caused issues that GM is reluctant to fix.

The HP-MTF is manual fluid and does not have the same issues. If you use the HP-MTF, allow enough fluid for a 'flush and fill'. Gotta get the OEM fluid out of the transmission cooler and lines.

Recommended quarts needed for a flush?

 

[BKC1]

100% not required, but certainly won't hurt. I used to do a -6060 fluid swap at the end of every racing season.

They made it easier on the Blackwing by moving the temp sensor to a different port.

Just be sure to use the GM OEM fluid OR the TREMEC HP-MTF. Don't go into the redline/amsoil, etc trap.

If you use the GM fluid, follow the procedure to the letter, with the expansion properties of the ATF, overfilling the -6060 and getting the fluid hot has caused issues that GM is reluctant to fix.

The HP-MTF is manual fluid and does not have the same issues. If you use the HP-MTF, allow enough fluid for a 'flush and fill'. Gotta get the OEM fluid out of the transmission cooler and lines.

What problems, specifically? What's the thermal coefficient of expansion of HP-MTF or Dextron III or D4 ATF?

This is you:

Hot Trans Temps/Overfilled M6 - CAMARO6

Hot Trans Temps/Overfilled M6 Mechanical Maintenance: Break-in / Oil & Fluids / Servicing

www.camaro6.com

Most of this comes from the Camaro community, who half-read my posts 12 years back on the D4 ATF + 75W80 MTL mixture and only ran D4 ATF in their transmissions. Of course you're going to have problems running straight ATF--it'll sound like a rock grinder, not to mention it'll shift like garbage.

It's not that Redline or AMSOIL don't make oil suitable for the T-56 or TR-6060, or that Dextron III and HP-MTF oils contain some special sauce; the root cause of the problem is lazy research. Ultimately, if you want to run Dextron III or HP-MTF, do it. If you want to fill your transmission per Tremec recommendations, do it. It doesn't matter, but be my guest.

Overfilling doesn't help or hurt--the T-56 and TR-6060 have a vent so there's no overpressure potential. All fluids expand under heat, and as long as you don't lose the bubble (e.g. by rotating the transmission and literally filling it up so that the vent can't operate) it doesn't matter what the coefficient of thermal expansion is.

The discussion about churning and frothing due to overfilling is unbelievable levels of stupid because if you have any oil in the case (well, beyond a half a quart), the gears will be immersed in fluid and churning it up. That's what the antifoaming agents (e.g. silicon) are for.

How do you think the oil gets to the gears on cars without an oil cooler pump? What happens when you accelerate hard or corner hard? Where does that oil go? Clearly it's not a problem for oil to get everywhere--in fact, it should and does get everywhere. Obviously this is not to say that you should roll the transmission onto its right side and fill 'er up. The losses from submerging the gears would be stupid high and you would be stupid for wasting your money that way.

The point is, if you're worried about transmission failures or accelerated wear, you should be worried about having the right friction modifiers in the oil and complete lubrication (as opposed to starvation)--those are the things that kill transmissions.

 

[MatthewAMEL]

Great in-depth breakdown!

When I got my 6th Gen, I bought the service manual (pg 12160 in mine). It was emphatic about the procedure to not overfill the case. The whole 'bend mechanics wire 1/8' in length' or remove 8oz once you fill to the bottom of fill port.

When researching best care and feeding of the -6060, I called TREMEC and the person who I eventually corresponded with said the overfill precaution was due to the expansion properties of ATF/Dexron. He said when you buy the same transmission directly from TREMEC or a supplier like Summit, they recommend their HP-MTF (or equivalent) and there was no need to do the 'overfill procedure' since MTF does not have the same expansion issues as ATF/Dexron.

What is interesting (anecdotally, perhaps) is the manual transmission in the V6 6th Gen does not use Dexron and has a fill/drain procedure that is 'fill to the bottom of the fill port and call it done'. The M6 in the V6 is NOT a -6060.

 

[Dirkbg]

Recommended quarts needed for a flush?

CT4BW

 

[AC2024]

Great in-depth breakdown!

When I got my 6th Gen, I bought the service manual (pg 12160 in mine). It was emphatic about the procedure to not overfill the case. The whole 'bend mechanics wire 1/8' in length' or remove 8oz once you fill to the bottom of fill port.

When researching best care and feeding of the -6060, I called TREMEC and the person who I eventually corresponded with said the overfill precaution was due to the expansion properties of ATF/Dexron. He said when you buy the same transmission directly from TREMEC or a supplier like Summit, they recommend their HP-MTF (or equivalent) and there was no need to do the 'overfill procedure' since MTF does not have the same expansion issues as ATF/Dexron.

What is interesting (anecdotally, perhaps) is the manual transmission in the V6 6th Gen does not use Dexron and has a fill/drain procedure that is 'fill to the bottom of the fill port and call it done'. The M6 in the V6 is NOT a -6060.

But this is where I get REALLY confused by this thread. The service manual indicates 88861800 of the MTF. Per GM / AC Delco 88861800 is 75w90, not ATF.

 

[BKC1]

Right, the OEM fluid is NOT ATF. It is gear oil. Running straight ATF is bad. I think people are confused by that last statement because the internet is saturated with threads recommending Mobil 1 ATF and straight D4 ATF. Those are bad recommendations, and if you dig, you'll find out that those people later reverted the oil or ghosted.

If you don't know what to do, follow the OEM recommendation. If you want to make an incremental improvement while you're down there, focus on installing a remote bleeder line (which is super worthwhile) and a magnetic drain plug.

 

[MatthewAMEL]

Right, the OEM fluid is NOT ATF. It is gear oil. Running straight ATF is bad. I think people are confused by that last statement because the internet is saturated with threads recommending Mobil 1 ATF and straight D4 ATF. Those are bad recommendations, and if you dig, you'll find out that those people later reverted the oil or ghosted.

If you don't know what to do, follow the OEM recommendation. If you want to make an incremental improvement while you're down there, focus on installing a remote bleeder line (which is super worthwhile) and a magnetic drain plug.

Well, it certainly is ATF in the BW5 with the -6060.

And if you go to Redline and others to find what their equivalent product is...it's 'straight' ATF.

D4 ATF - Quart​

• Our most versatile ATF, use where Dexron III®, Dexron II®, Mercon® and Mercon V® fluids are recommended, for use in automatic, manual transmissions and power steering
• Popular applications: Toyota Type T-III and T-IV, Honda ATF-Z1, Nissan Matic D, J & K, Diamond SP-II, SP-III, Mazda ATF M-V, most BMW and Audi/VW automatic transmissions
• Also used with manual transmissions and transaxles like T-5, T-45, T-56 and late-model BMW, provides a GL-4 level of gear protection
• Excellent cold weather operation

 

[rubberduck]

 

[AC2024]

Right, the OEM fluid is NOT ATF. It is gear oil. Running straight ATF is bad. I think people are confused by that last statement because the internet is saturated with threads recommending Mobil 1 ATF and straight D4 ATF. Those are bad recommendations, and if you dig, you'll find out that those people later reverted the oil or ghosted.

If you don't know what to do, follow the OEM recommendation. If you want to make an incremental improvement while you're down there, focus on installing a remote bleeder line (which is super worthwhile) and a magnetic drain plug.

Got it. Thank you! But then based on your prior post, if I drain and fill with the OEM AC Delco gear oil, should I still under fill by 1/8" or fill to run out? The maintenance procedure indicates to underfill, and presumably they assume use of OEM fluids, so that's probably what I'll do.

That said, do you think a break in 6MT drain and fill is appropriate? I dont want to do more harm than good if it's not neccesary, but I've always done a break in drain and fill along with the diff and motor oil and then ~30K intervals.