My 2021 MX-5 is coming up on 20,000 miles of multi-duty use - daily driving, track days, autocross, etc. Thinking about replacing the transmission and maybe diff fluid. My main goal is just preventative maintenance to make it last. I'm not trying to improve shift feel or whatever...unless I don't know what I'm missing.
So what should I do, stick with the Mazda stuff? Ford Motorcraft unicorn tears? Redline MT90, MTL? Motul?
I used the Motorcraft stuff. It was fine. I suspect any of the others would be fine too.
I would just run a quality synthetic that matches the weight called for and whether it calls for GL-4 or GL-5. Redline, Motul, etc.
For instance my BRZ calls for 75w-85w in both the transmission and the differential. But GL-4 in one and GL-5 in the other.
I used Motorcraft unicorn tears in my 6 speed NC transmission and was happy with the performance. I was a bit surprised at how bad it looked after 8k miles including 6 hours of track time. I tried the Redline and it did not seem to shift as well so I went back to Motorcraft and stuck with it.
I'm seriously concerned about transmission durability, so i use a mix of Redline mt90 and lightweight shockproof. Shifts better than the weak factory fill, but still not as smooth as some of my NB transmissions with redline Mt90
i use heavy shockproof in the diff as the capacity is small, the tires are sticky and the torque is increased
I think the best thing to do to ensure ND trans reliability is to add a cooler. We've logged fluid temps of 300F in track use on a stock ND trans - and they don't come down for hours. Even street driving on the way home doesn't drop the temps. Gives you more capacity as well. Same with the diff.
The Global Cup cars use coolers on both, and their fluid is a full synthetic 75W-90.
https://flisperformance.com/flis-performance-lubricant-bulletin/
Keith Tanner said:I think the best thing to do to ensure ND trans reliability is to add a cooler. We've logged fluid temps of 300F in track use on a stock ND trans - and they don't come down for hours. Even street driving on the way home doesn't drop the temps. Gives you more capacity as well. Same with the diff.
The Global Cup cars use coolers on both, and their fluid is a full synthetic 75W-90.
https://flisperformance.com/flis-performance-lubricant-bulletin/
I can only imagine what mine are whilst tracking in triple digits...
Me also:
In reply to Keith Tanner :
Old post here, but wondering if there is a transmission cooler you recommend. Market looks sparse for a ready made product.
Well, FM used to offer a good one but sales were not good enough to justify keeping it in stock. People like Andy with their heads in the sand :)
I don't know if there is an alternative other than the Global Cup one from Flis Performance.
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