2023 Mazda Miata Transmission & Rear Diff Oil

[Phishin]

2023 Miata Club with Brembo/BBS/Recaro Package. Driven by my 20 year old son.

Car has 20k miles. He's been running Redline oil and RP oil filters (recommended by me). He drives it hard.

He's wanting to change the transmission oil. What do you guys recommend? Is the Ford XT-M5-QS still the preferred choice here?

And regarding the rear differential, Redline 75w90 GL-5? Or you guys like something else?

 

[ARCOgraphite]

For the rear.
No need for pricy gear oil out back. Contains LSX adds where needed. 15 bucks.

 

[bdcardinal]

Whatever meets this spec:

 

[ARCOgraphite]

SG1 LL. Really. C'mon Mazda. For that Lil pipsqueak tuna can?!
What's with the intentional obfuscation?

 

[tcp71]

Tried the redline MTL 75w80, Ford XT-M5-QS, Amsoil and valvoline options on the CX-5 MT. Ended up with this as the smoothest and best choice for our CX-5:

 

[MRC01]

The general rule is GL-5 in differentials and GL-4 in a transmission or shared differential/transmission.
The Miata diff is separate from the transmission so that suggests GL-5 in the diff and GL-4 in the transmission.
PS: I've used Redline GL-4 75w80 in transmissions with good results, and it's popular in the SCCA autocross world, where they drive their cars hard.

 

[Phishin]

Tried the redline MTL 75w80, Ford XT-M5-QS, Amsoil and valvoline options on the CX-5 MT. Ended up with this as the smoothest and best choice for our CX-5:

View attachment 272315

Anything but Amsoil. I can't get myself to buy this over-hyped Walmart brand junk.

And ARCO, I'm not running cheap diff lube just so I can save a few bucks. No Thanks.

And correct, I agree. GL-4 in the Gear Box. GL-5 in the Rear End.

Any Miata owners here with advice?

 

[bdcardinal]

Anything but Amsoil. I can't get myself to buy this over-hyped Walmart brand junk.

And ARCO, I'm not running cheap diff lube just so I can save a few bucks. No Thanks.

And correct, I agree. GL-4 in the Gear Box. GL-5 in the Rear End.

Any Miata owners here with advice?

I sell a lot of the XT-M5-QS Ford fluid to Miata owners. Just had a ND owner in raving about it.

 

[martinq]

If you don't mind the cost then stick with top-tier products from Red Line, Amsoil or HPL. You could also look into Motul.

 

[dnewton3]

I owned a new 2019 ND2 Club with the Brembo/BBS. Ran the OE fluids and then changed to Ford MTF in the trans and used ST 75w-90 in the rear. 33k miles in three years.

I traded it for a new 2023 ND2 GT. Ran the OE fluids and then changed to Red Line MT-LV in the trans and Valvoline Syn 75w-90 in the rear. 20k miles in two years (still have it). I was told (and therefore expecting) that the LV fluid would really improve the shift quality ... didn't happen in any appreciable manner.

After 50k miles of different fluids, including OE and aftermarket, in two different MX-5s, I can honestly say folks overthink this. It is difficult, if not impossible, to really distinguish a difference in terms of "feel". I don't think the RL does any better than the Ford fluid. And I didn't perceive any difference in the ability of the Torsen diff to properly operate between the OE, ST and Valvoline.

Use what you and your son see fit, but I think many folks are brand loyal to suit emotional bias.

 

[ARCOgraphite]

Anything but Amsoil. I can't get myself to buy this over-hyped Walmart brand junk.

And ARCO, I'm not running cheap diff lube just so I can save a few bucks. No Thanks.

And correct, I agree. GL-4 in the Gear Box. GL-5 in the Rear End.

Any Miata owners here with advice?

Properly priced but well performing; GL-5 gear lube ain't new science.

***deleted some unnecessary additional harassment***

 

[JettyLife]

Any Miata owners here with advice?

Walter Motorsports rebuilds ND transmissions and recommends Motul 75w140 in the trans. His advice is to drain Amsoil immediately and do not drive the car with Amsoil in the trans. I can't remember the exact reason why. The Motul 75w140 is listed by Motul as being GL-4 and GL-5 safe for yellow metals. People say it can be notchy on cold mornings though. My ND is garage kept so I don't really have that issue. The transmission feels great once it's got some heat in it, very smooth and enjoyable to drive.

 

[jtwrace]

Walter Motorsports rebuilds ND transmissions and recommends Motul 75w140 in the trans. His advice is to drain Amsoil immediately and do not drive the car with Amsoil in the trans. I can't remember the exact reason why. The Motul 75w140 is listed by Motul as being GL-4 and GL-5 safe for yellow metals. People say it can be notchy on cold mornings though. My ND is garage kept so I don't really have that issue. The transmission feels great once it's got some heat in it, very smooth and enjoyable to drive.

https://waltermotorsports.com/why-your-nc-mx-5-needs-gl-4-transmission-fluid

 

[JettyLife]

https://waltermotorsports.com/why-your-nc-mx-5-needs-gl-4-transmission-fluid

Wrong generation... Here's the link for their ND Miata, down the bottom they say, "Again, we can only recommend Motul Competition Gear 75W-140 for any ND transmission."
They're also all over the forums saying the same thing. Also Motul 75w140 is GL-4 / GL-5 compatible.

https://waltermotorsports.com/our-specialties/nd-6-speed-transmission

 

[jtwrace]

Wrong generation... Here's the link for their ND Miata, down the bottom they say, "Again, we can only recommend Motul Competition Gear 75W-140 for any ND transmission."
They're also all over the forums saying the same thing. Also Motul 75w140 is GL-4 / GL-5 compatible.

https://waltermotorsports.com/our-specialties/nd-6-speed-transmission

strange

 

[Pablo]

Walter Motorsports rebuilds ND transmissions and recommends Motul 75w140 in the trans. His advice is to drain Amsoil immediately and do not drive the car with Amsoil in the trans. I can't remember the exact reason why. The Motul 75w140 is listed by Motul as being GL-4 and GL-5 safe for yellow metals. People say it can be notchy on cold mornings though. My ND is garage kept so I don't really have that issue. The transmission feels great once it's got some heat in it, very smooth and enjoyable to drive.

That just makes zero sense. Just didn't like the thought of it??

Anything but Amsoil. I can't get myself to buy this over-hyped Walmart brand junk.

And ARCO, I'm not running cheap diff lube just so I can save a few bucks. No Thanks.

??? Non-sensical really. GL-4 for the transmission

https://www.amsoil.com/p/amsoil-75w-90-manual-transmission-transaxle-gear-lube-mtg/?zo=515729

 

[pbm]

Whatever meets this spec:

View attachment 272313

I wonder why Mazda doesn't recommend FZ ATF for the Miata as they do for all their other ATs of that year?

Also, Royal Purple 'Maxgear' 75w90 is recommended for both GL-4 and GL-5 use. I've used it in place of Mazda's 75w85 SG1 LL in our Mazda CX-30's differential and transfer case without issues. Maybe 75w140 would be OK in Forth Worth, Texas heat (where Walter Motorsports is based) but I wouldn't use it up north....JMO. Torco also makes an MTL that claims to be "yellow metal safe"...IIRC it's called MTF.

PS: While I've never used Amsoil products I certainly don't think they are 'junk'. Amsoil makes excellent products but I change my fluids frequently enough to feel good using off the shelf fluids that meet the required specs.

 

[bdcardinal]

I wonder why Mazda doesn't recommend FZ ATF for the Miata as they do for all their other ATs of that year?

Also, Royal Purple 'Maxgear' 75w90 is recommended for both GL-4 and GL-5 use. I've used it in place of Mazda's 75w85 SG1 LL in our Mazda CX-30's differential and transfer case without issues. Maybe 75w140 would be OK in Forth Worth, Texas heat (where Walter Motorsports is based) but I wouldn't use it up north....JMO. Torco also makes an MTL that claims to be "yellow metal safe"...IIRC it's called MTF.

PS: While I've never used Amsoil products I certainly don't think they are 'junk'. Amsoil makes excellent products but I change my fluids frequently enough to feel good using off the shelf fluids that meet the required specs.

Probably because that automatic is still an AW sourced unit and not an in house Skyactiv unit.

 

[Dave Hess]

I owned a new 2019 ND2 Club with the Brembo/BBS. Ran the OE fluids and then changed to Ford MTF in the transmission and used Supertech 75w-90 in the rear. 33k miles in three years.

I traded it for a new 2023 ND2 GT. Ran the OE fluids and then changed to Red Line MT-LV in the transmission and Valvoline Syn 75w-90 in the rear. 20k miles in two years (still have it). I was told (and therefore expecting) that the LV fluid would really improve the shift quality ... didn't happen in any appreciable manner.

After 50k miles of different fluids, including OE and aftermarket, in two different MX-5s, I can honestly say folks overthink this. It is difficult, if not impossible, to really distinguish a difference in terms of "feel". I don't think the RL does any better than the Ford fluid. And I didn't perceive any difference in the ability of the Torsen diff to properly operate between the OE, Supertech and Valvoline.

Use what you and your son see fit, but I think many folks are brand loyal to suit emotional bias.

That’s good to know.

I’m thinking about buying a new soul red Miata.