2021 MX-5 Miata 6MT Gear Lube

ThatNavyGuy

ThatNavyGuy

Joined
May 2, 2022
Messages
69
It’s coming up on time to swap out the gear lube on my Miata. Manual says to only use Mazda Long Life Gear Oil IS to maintain the original shift feel, however this stuff is hard to find and when you can find it they ask for $35+ per quart. The manual also says 75W-90 GL-4 is acceptable however shifting in cold weather may be affected.
I love the feel of this transmission and want to keep it that way.
I’ve searched several forums and there is a lot of different opinions on whether or not the 75W-90 feels the same or worse. Lots of good reviews on Redline MT-90, but I’ve also read that the Mazda oil is actually a 75W-80, which Redline also has a flavor of.
Can anyone confirm that the Mazda original gear lube is indeed 75W-80? Also looking for any helpful suggestions on what you would or have used and how it performed.
 
Go to a Ford dealer and buy Motorcraft Fluid XT-M5-QS.
Loved in the Mazda community. I used it in a 2013 GTI and when I bought it, the bottle said made in Germany. The crazy price on Amazon is because it's out of stock. Tons of Miata 5 star reviews.

EDIT, I didn't pay attention to your model year and would probably spend the money on the OE fluid.
 
In my S2000 and Turbo Miata 6 speeds, I'd use Royal Purple Syncromax with great results. Also used Mobil 1, ATF with superb results. I currently have Royal Purple in my older Jag's 5 speed. There really is no magic fluid, and any of the light weight MTF fluids will give great shift feel.
 
ThatNavyGuy said:
Manual says to only use Mazda Long Life Gear Oil IS to maintain the original shift feel, however this stuff is hard to find and when you can find it they ask for $35+ per quart. ...... I love the feel of this transmission and want to keep it that way.
Click to expand...

Two quarts required? $70 for the fill, how much is a new transmission?
$6000 or $7000? I certainly know I'd make my choice.


ThatNavyGuy said:
Can anyone confirm that the Mazda original gear lube is indeed 75W-80?
Click to expand...

Very most OE MTFs are 75W (or actually 70W-75ish) for many years
(25 years or so). If Mazda's MTF is actually a 75W-80 it's an exception
for today's standards.

ps:
OE VW G 052 527 is roughly $60 per liter. :oops:
 
930.engineering said:
Two quarts required? $70 for the fill, how much is a new transmission?
$6000 or $7000? I certainly know I'd make my choice.




Very most OE MTFs are 75W (or actually 70W-75ish) for many years
(25 years or so). If Mazda's MTF is actually a 75W-80 it's an exception
for today's standards.

ps:
OE VW G 052 527 is roughly $60 per liter. :oops:
Click to expand...
It’s not so much the “cost” as it is the “hard to find”, and I’m sure there are aftermarket alternatives that would work just as well if not better that are easier to obtain.
 
Manual transmission fluids aren't all that different. For thinner mtf's this honda one is well regarded and isn't overpriced. Most small car manuals usually use an sae 80 type so i'd be surprised if it was a 90 grade.

"Honda Fluid 08798-9031 is a manual transmission fluid with a viscosity of 75w-80. It's a PAO-based, full synthetic, low-viscosity transmission oil that's designed for modern manual transmissions"

After looking up that mazda fluid it comes back as an 80 grade so yes it's the thinner kind which is unsurprising.


https://www.hondapartsconnection.co...da-manual-transmission-fluid-1-quart-87989031
Has it for a lot less but you pay flat shipping,
 
JavierH19 said:
Manual transmission fluids aren't all that different. For thinner mtf's this honda one is well regarded and isn't overpriced. Most small car manuals usually use an sae 80 type so i'd be surprised if it was a 90 grade.

"Honda Fluid 08798-9031 is a manual transmission fluid with a viscosity of 75w-80. It's a PAO-based, full synthetic, low-viscosity transmission oil that's designed for modern manual transmissions"

After looking up that mazda fluid it comes back as an 80 grade so yes it's the thinner kind which is unsurprising.


https://www.hondapartsconnection.co...da-manual-transmission-fluid-1-quart-87989031
Has it for a lot less but you pay flat shipping,
Click to expand...
Thanks!
 
skyactiv said:
Go to a Ford dealer and buy Motorcraft Fluid XT-M5-QS.
Loved in the Mazda community. I used it in a 2013 GTI and when I bought it, the bottle said made in Germany. The crazy price on Amazon is because it's out of stock. Tons of Miata 5 star reviews.

EDIT, I didn't pay attention to your model year and would probably spend the money on the OE fluid.
Click to expand...
It was this when I had my 2004 that solved the 1-2 "crunch" ,virtually the entire Miata club was using it. It seems to make a really difference in the Miata 6-speed, a remarkable game changer.
 
Speedy3861 said:
It was this when I had my 2004 that solved the 1-2 "crunch" ,virtually the entire Miata club was using it. It seems to make a really difference in the Miata 6-speed, a remarkable game changer.
Click to expand...
This.

When I had my 2006 MX5 (5 speed), I changed to this fluid and got smoother shifts. It kept the "notchiness" flavor of the old school but was very smooth, much smoother than original. Hope that makes sense.
 
Cujet said:
In my S2000 and Turbo Miata 6 speeds, I'd use Royal Purple Syncromax with great results. Also used Mobil 1, ATF with superb results. I currently have Royal Purple in my older Jag's 5 speed. There really is no magic fluid, and any of the light weight MTF fluids will give great shift feel.
Click to expand...
The royal purple gear oil in my RX-7 is great. Smooth shifts.
 
At 2K miles I changed the fluid on my 2018 FIAT 124 Spider (Mazda tranny) with the Ford juice. The factory fill was pretty glittery and crunchy cold1-2 shifts were eliminated.
Since the Amsoil product selector shows no 75W80 tranny fluid for the current Miata, one could assume that’s what the factory fill is.
 
Last edited:
ThatNavyGuy said:
It’s coming up on time to swap out the gear lube on my Miata. Manual says to only use Mazda Long Life Gear Oil IS to maintain the original shift feel, however this stuff is hard to find and when you can find it they ask for $35+ per quart. The manual also says 75W-90 GL-4 is acceptable however shifting in cold weather may be affected.
I love the feel of this transmission and want to keep it that way.
I’ve searched several forums and there is a lot of different opinions on whether or not the 75W-90 feels the same or worse. Lots of good reviews on Redline MT-90, but I’ve also read that the Mazda oil is actually a 75W-80, which Redline also has a flavor of.
Can anyone confirm that the Mazda original gear lube is indeed 75W-80? Also looking for any helpful suggestions on what you would or have used and how it performed.
Click to expand...
I wrote to Redline to ask which fluid they recommended for my 2016 ND Miata 6spd. They responded that I should use MT-90. That's what I used 5 years and 20,000 miles ago. The shift quality seemed the same or maybe a little better in the cold and has remained good.
 
I've tried Valvoline Syncromesh, Ford synthetic MTF and Redline MTL in the skyactiv 6spd before settling on the Amsoil fluid. Not sure if the miata has the same transmission.

If you dig deep enough amsoil has yellow metal test information and it passes gl-4 without issue. I'm not an amsoil fanboi but for this application it works better than the others I've tried.
 
eagle14 said:
This.

When I had my 2006 MX5 (5 speed), I changed to this fluid and got smoother shifts. It kept the "notchiness" flavor of the old school but was very smooth, much smoother than original. Hope that makes sense.
Click to expand...
From my notes from my Miata, the Motorcraft XT-M5-QS is made in Germany and was formulated to make the Getrag transmissions run smoothly, full synthetic 75W-90. It was/is the preferred fluid for Miata and other Mazda 5 & 6 speed manual transmissions. Once I tried it, never looked for anything else.
 
Redline 75w90 gl5 with limited slip additive. I had both 75w90 gl5 LS for the rear end and redline mt90 gl4. Both worked flawlessly in a 2019 nd2 Miata I used to own. Use the redline website to tell you what you need. The mt90 in the transmission was night and day, it shifted like butter after. Not noticable different in the rear.
 
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