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Discussion Starter #1
Hello everyone!

So, I've got a new 2018 Mazda 6 with a manual. Only about 2k miles on it thus far. And like others, I've had some small but definitely present issues with shifting. Sometimes it doesn't like to go into first or reverse, feels a bit notchy, and sometimes I can feel just a touch of grind, especially between 1st and 2nd.

And so after looking around here and getting a feel for things, I decided to try something. I got some Redline MTL 75W80 GL4, and topped off the transmission. I used Mitchapalooza85's excellent DIY for guidance. I got at least half a quart in, and maybe as much as 3/4s (hard to estimate how much was left in my little hand pump).

I can definitely feel a difference. It snaps into gear more positively, and the notchiness is definitely reduced. The stick actually feels heavier. I haven't put more than a handful of miles on it since then, so I'd guess it'll improve more with a little time.

In any case, if I have issues or updates, I'll post them here.
 

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I've been running the MTL in my MTX since I changed the fluid the first time. It's now approaching 180k miles and is fine... material improvement was noted immediately in notchiness when I switched to it.
 

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Very good to hear that you made progress with this matter. There is also a TSB in regard to shift mechanism alignment. It applies to the Mazda3 - but 'cause the shifter and shift cable arrangements are totally the same as the Mazda6 - it applies here, too. TSB no. 05-007/13. I can PM that to you if you wish. Oh, in addition, interior upper console removal is necessary... pretty easy - but it MUST BE done carefully. I have those instructions, too, but for the 2016 - 2017.5. Likely minor differences with the 2018.

Here (below) is the account of the trials and tribulations that one fellow had with his 6MT Mazda6.... If you read to the very end of the forum / thread - you can see that though it sounds totally unlikely, the realignment of his shifter had an incredible impact on exactly what you are experiencing.

I will be undertaking this TSB 'real soon... and I may indeed go to the Redline 75W-80 fluid (i have two quarts ready-to-go).

Here is the thread: https://forum.mazda6club.com/mtx-transmission-discussion/297825-crunchy-manual-transmission.html

Good luck... and please keep folks informed!
 

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... and topped off the transmission. I used Mitchapalooza85's excellent DIY for guidance. I got at least half a quart in, and maybe as much as 3/4s (hard to estimate how much was left in my little hand pump).
I would have done a full fluid drop (when hot) and the addition of a full amount of the Redline GL4. It would be necessary, of course, to have the car elevated (and level).

I am not sure you are getting the full benefit of the Redline if you do not do this full fluid replacement.
 

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Discussion Starter #5
Thanks! I saw instructions for the realignment, and I definitely have that up next to try if I'm not satisfied after a few weeks. I didn't want to risk yanking on consoles just yet.



I considered a full drain and fill, but I decided not to. It seems like to me that the real issue is that there's not enough fluid, not that the fluid itself is substandard. Topping it off with whatever Mazda put into it probably would have helped just as much. I just didn't want to spend another $40 on fluid and have to deal with the waste, which is barely touched fluid. Seems wasteful.



Has the feeling around here been that Mazda's fluid itself isn't quality?
 

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The Redline MTL 75W-80 GL4 is apparently a full-synthetic (not sure if it is Gas-To-Liquids - GTL or PAO... and I'm not sure that matters, here) - but they apparently have some unique friction properties that in MOST cases improves, markedly, the shift-feel. I don't think the Mazda-branded fluid is in the same league.

Others?
 

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It is a full synthetic and is quite high-quality.

With that said I wouldn't be surprised at all if the stock Mazda MTX fluid is too. Most are these days, even though in a MTX there's less of an issue than with an ATX in that regard. The big deal with an MTX is to never, ever run anything that has "GL-5" anywhere on the label. It will destroy the synchros VERY reliably.

GL-5 oils are great in differentials -- including ones with roller lockers (which most locking diffs are.) But the friction modifiers in them bond to form a film that is stronger than the brass in synchronizers, which means that instead of film shearing (as it is supposed to) the synchro material shears!

Taking the console off to perform the alignment procedure is trivially easy if you have reason to believe yours is off and it's a very low-risk procedure. I've not really had a reason to do it on my car but may somewhere around 200k miles simply due to the potential for stretch in the cable system over time.
 
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