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 tranny or shared differential/tranny.
The Miata diff is separate from the tranny so that suggests GL-5 in the diff and GL-4 in the tranny.
PS: I've used Redline GL-4 75w80 in trannys 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***