I’m looking for technical help or recommendations on: __Gearbox oil
⸻
Red Line 75W90 (MT-90) – 2019 ND2 RF 2.0
I’m relatively new to MX-5 ownership and have been reading up on some of the gearbox issues reported with the ND models. With that in mind, I’m planning to change the gearbox oil annually as a precaution.
I’ve been considering Red Line MT-90 (GL-4 75W90), as it’s often recommended, but it is noticeably more expensive than other options. I’m not too concerned about the cost if it genuinely offers better protection and shift quality — but I don’t want to waste money or risk causing harm to the gearbox either.
Would appreciate any feedback from owners who’ve run Red Line MT-90 in their ND2. Cheers!
He talks about gearbox oil and has some interesting facts that may influence your choice.
I am using the Millers oil and can confirm that the cold gear change was better with the Mazda oil. I have not found a source for the Mazda oil in the UK.
It is not an issue for me as it is easy to deal with by being careful and the gear change becomes good after a mile.
Very interesting watch…Mazda OEM gearbox looks like the way to go, but whereabouts can I get some.
Surely the dealers must have it for when they service the MX-5
I have not found any in the UK but if you do then please let us know. I suspect you can buy the big drum from a dealership but not the 1 litre. There are a number of products to the Mazda viscosity spec available but I have not heard of anyone using them.
Like with most things it is best not to overthink these things.
Personally I’d stay way from 75W-90 on the ND.
This guy used it, even the hallowed Millers loved by some on here, and said it was awful when cold.
He correctly said the factory fill is 75W-80 (not 90). I can attest to that as I wrote to Mazda too a few years ago, and they said the same to me.
If you plan to do it annually, you could buy the factory oil, but they only do it in a 20L drum. part number which Mazda gave me is K020-W0-042R
Again, Flander’s also was given this number/used this. Fast forward to 15:17 on this (different video to the above one) video to see: https://www.youtube.com/watch?v=t_vdoG4F4bE
Good question, and it depends if even they use the proper stuff. When I had mine done, I actually brought in alternative oil, which the service manager said was fine (he knows what I’m like lol), but said ‘before we do, this is what we would put in it’…and showed me the original stuff in the big 20L drum So I said, ‘cool, put that in, don’t worry about what I got’, and I took mine back and let them use theirs. I actually noticed the change was even better from the first 1st to 2nd shift driving out.
It’s hard to put a price on that gearshift being how you like it. If you do, maybe it’s best to suck it up and get the big drum. You’re in a good position if you can do it yourself anyway (I can’t).
Note, I say ‘even if they (dealers) use the proper stuff’, as if you look over the forum historically, on occasions when people have had their gearbox oil changed, sometimes the dealer has put in ‘alternative’ stuff.
That exact question, whether the dealer actually uses the correct stuff—had definitely crossed my mind too.
I’ll more than likely go ahead and buy the 20L drum. It works out better long-term, and I could probably sell a few litres to some local MX-5 owners to offset the cost. You’re right though—when the shift feels spot on, it’s worth every penny.
Thanks for the input. I’m not too worried about the cold 1st to 2nd shift—it’s more important to me that all the shifts feel good and slick once everything’s up to temp. That said, gearbox protection is a big priority, so I’m looking for something that offers both smooth shifting and solid long-term durability.
No mention of the Redline MT90 that Google recommended?
Flanders mentioned a headache for 20 minutes or so, and the problem with a mile (or 20 or so mins in the case of Flanders) is presumably the OP’s car don’t do that now. To each their own but if someone said to me your smooth gearshift from the get go is now going to be a headache for a mile (or 20 mins, going by another user) if you use gear oil X, personally I’d pass. The Miller’s 75W-80 might be different. My probably unjustified beef is that oil is gl4 and gl5.
The two I used for servicing use 0w-20, when one of them used to use 5w-30. In fact I might say put 5w-30 in it next time Saying that, doing 1-1.5K miles a year there probably won’t be any difference. You’re right though, I guess what goes in there (engine oil) depends on the dealer’s drums
Just to give my 2 cents on this, i swapped out the OEM fluid with MT-90 which is a GL-4 oil last Sunday actually and to me it does shift better in my view.
I haven’t had any issues myself with notchiness and was attributing the notchy feel that Richard was talking about in his video to the fact that the Millers he used is a GL4 compatible (it actually says GL-5 on the bottle datasheet). But i may be wrong and that may have nothing to do with it it’s just something worth noting.
At the end of the day I would assume that so long as the oil used is in spec in the listing in the owners manual the gearbox should not have issues. If this isn’t the correct specification then really Mazda should let us owners know so we can make sure that the correct specification is used
So I said, ‘cool, put that in, don’t worry about what I got’, and I took mine back and let them use theirs. I actually noticed the change was even better from the first 1st to 2nd shift driving out.
it’s just something worth noting.