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How often to change transmission fluid?

15K views 24 replies 14 participants last post by  M6dad87 
#1 ·
Hi, just want to get some advice on how often to change transmission fluid.

I have a 2018 M6. Some say sealed for life but heard stories that only realise it is not the case until too late...

So, per 20k km? or ...?

Thanks.
 
#3 ·
I did mine at 50,000 km.



If you don't, and someone didn't, the car reached about 470,000 km before going kaput.

 
#6 ·
Definitely change the fluid, highly recommend dropping the pan and replacing the filter!

I plan to drain and refill the transmission every 10-20k miles, while changing oil, knowing it only replaces a portion of the liquid, where the goal is to replace all fluid every 50k miles.

I have been using Dex VI transmission fluid + Lubegard Platinum 1oz per 1qt of transmission fluid, to raise the fluid additives to meet the Mazda FZ specifications. Been running great on 3 different Mazda Skyactivs, and mine's been supercharged for 12k miles and performing beautifully.

I too plan to drive this car for a while, I am planning on 10-15 years more (@Archerfish not sure I can get 20 more years out of it with the supercharger and multiple racing events per year, but we'll see)

If you don't think it's necessary check my little video, this is with only 40k miles:
 
#8 · (Edited)
If it does not have a torque converter*, and we know that torque converters without drain plugs (like almost all of them these days) hold a lot of fluid, then I wonder what % of fluid gets changed with a pan drop? Now it might be that the wet clutch pack is contained in an envelope that is just like a TC... And it too might retain fluid. For that matter, said unit may not be disassembleable... or easy-draining.
* Correction: it does have a torque converter... The above points are therefore more or less nullified...
 
#7 ·
and Here's a how to a friend made, he's running the same fluid as me and he's already put almost 30k miles on it since changing the fluid and it's been great (I think he's over 150k miles now)

 
#9 ·
I am using a 35k mile interval with mine. Mazda does not mention a recommended change interval so we are all on our own with this. Old wives' tales are the order of the day here, but with a good dose of practicality in most cases. I don't think you would be hurting anything by changing at 10k, but I'm sure extending that interval to twice or three times as long would be perfectly fine as well. In fact, I don't think changing at 50k would be problematic either. I'll be tackling this again in a few days (hopefully) as I will be reaching 35k since my last change in February last year. I've already obtained the fluid from rockauto.com and this time I got the Idemitsu brand.



My last change I got the Beck/Arnley brand which is still available, but is a wee bit more expensive ($6.20 vs $6.79).



Idemitsu is the OEM for Mazda's fluid so I'll be using that for now, as long as it's available. B/A will be my fall-back.
 
#10 ·
I am using a 35k mile interval with mine. Mazda does not mention a recommended change interval so we are all on our own with this. Old wives' tales are the order of the day here, but with a good dose of practicality in most cases. I don't think you would be hurting anything by changing at 10k, but I'm sure extending that interval to twice or three times as long would be perfectly fine as well. In fact, I don't think changing at 50k would be problematic either. I'll be tackling this again in a few days (hopefully) as I will be reaching 35k since my last change in February last year. I've already obtained the fluid from rockauto.com and this time I got the Idemitsu brand.



My last change I got the Beck/Arnley brand which is still available, but is a wee bit more expensive ($6.20 vs $6.79).



Idemitsu is the OEM for Mazda's fluid so I'll be using that for now, as long as it's available. B/A will be my fall-back.
That's the wrong kind of fluid.
Skyactiv Automatics need FZ spec fluid, not M5

I'm using the LubeGard additive to raise Dex VI to the level of Mazda FZ fluid

Wait so you've been running with M5 fluid for a while?
what color is it?
 
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#14 ·
I changed ATF on my 17 Touring last weekend at 95k. Since I plan on keeping it many years, I dropped pan and changed filter.
 
#25 ·
did you have any issues after that change? I have a 17 touring with 116k miles and never been changed due to the “lifetime” statement. I’d like to change mine but not sure if I should just do a fluid change (roughly 50%) or drop pan and change filter. If I had significantly lower miles it would be an easy answer but with my miles I’ve heard sometimes changing all that stuff can cause more harm than good (slippage, etc.).
 
#18 ·
The Redline MTL is, as well, 75W-80, GL-4. 'Lotsa folks like it. It will have a bit better cold-shifting performance (smoothness) than the OEM Mazda product, at least when the Redline MTL is new. Shearing of the oil in service, to my way of thinking, lessens the viscosity, which theoretically ought to make it feel better yet (for cold operation, in any case) than when new... but reportedly this product starts to shift in an inferior manner as it "wears"... I can't explain why.

As for me (and I don't pretend to be scientific, here) I like the OEM lubricant, and I guess I'd then prefer to baby it a bit when cold.

YMMV.
 
#19 ·
Red Line MTL was very good in our Mazda 5 M/T. As Cdn said, the excellent shift feel would degrade over the miles, but I'd change it and it'd be brilliant again. The closest dealer was a 4-hour drive away for much of the time we had that microvan, so I never tried to get a 'Mazda' MTL for it.
 
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#20 ·
I don't think wearing out over time is unique to Redline fluids -- any oil which is being used and sheared will start to break down over time, the additives wear out, and it becomes contaminated. The last time I put MTL in a car I ran it for 90k miles and the car still shifted just great. When I changed that 90k fluid with more MTL, there was only the slightest improvement in crispness and feel in the gear change. Would you expect anything different from any other gear oil?
 
#21 ·
Redline MTL, according to the Mfr, is designed with synchro cone clutch friction properties that are markedly different than its competitors. I don't know if this can be believed or not, but I do know that this product can- and often does improve synchro action for "grouchy" transmissions or transaxles. However, anecdotally, many folks do say a marked change in its behaviour occurs as time goes on. Apparently, substantially more so than most conventional manual gearbox lubricants. I personally have no experience with it, but I have definitely seen this matter reported-on...
 
#22 ·
I've noted no material difference over its service life; I do change MTX fluid on 50k intervals, more or less, but the improvement when I put it in over stock was immediate and I haven't noted any degradation over time, nor do I note a difference when I change it either.

YMMV but that's my experience in the "6".
 
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