Fluids and filters (NA, NB, NC, ND)
Oil, filters and gear oil are the things every Miata owner buys, and the transmission and differential fluid is where owners disagree most. This page lists what sellers describe and what one owner thread said. It is not a repair guide.
How to read it. Seller claims are as read on each seller's own page on 2 October 2026. Owner accounts are from Miata.net forum threads, dated below, and are individual opinions, not advice. There are no prices on this page, and nothing here was bought or tested.
| Seller | What it says it offers | Fits (as stated) |
|---|---|---|
| Moss Miata, oil filter by Mazda | a genuine Mazda filter, OE reference B6Y2-14-302-P1 | 1990-2005 NA and NB |
| Moss Miata, air filter by Mazda | a genuine Mazda air filter, OE reference B6S7-13-Z40 | 1990-1997 NA |
| Moss Miata, transmission fluid by Redline | Redline gear oil in 75W90 NS or MTL; the page says it is endorsed by the Miata Club of America and lists NA, NB, NC and ND years | 1990-2025 |
| Flyin' Miata, Redline 75W90 differential gear oil | synthetic gear oil for all stock Miata differentials, including factory limited slips and aftermarket clutch-style units; it says one quart is needed, that it is slightly thicker than the stock ND diff fluid, and that it is not for the transmission, where it recommends MTL or MT-90 | NA, NB and NC differentials |
| Flyin' Miata, ND maintenance tools | a collection listing a non-marring lug nut socket, a spill-free coolant bleeding funnel, a hub stand kit, thread-in oil funnels for the NC and ND and a clutch alignment tool; I read the listing, not the product pages | NC and ND |
Moss's search results also list a Jass Performance cabin air filter and housing for the NA and early NB, K&N air and oil filters, NGK copper spark plugs for 1994-2005 and a remote oil filter relocation kit; I did not open those pages. Moss's NC category page also lists a Mazda spark plug for 2006-2015.
What an owner thread said
- Gear oil for a 1996 (June 2021). An owner asked what to put in the transmission and differential of a 5-speed with a limited slip, because a Haynes manual gave different grades from what he found in stores. One reply said to use GL-4 only, not "GL-4 and GL-5", in the transmission, and that most owners on the forum swear by Motorcraft manual transmission fluid. The same poster said the differential needs a hypoid oil, GL-5, which in a synthetic is 75W-90, and that the factory manual's straight 90 weight is an antique spec. (Miata.net thread; first page, which is one person's view.)
Search results for other Miata.net threads say the same split: Redline MTL or MT-90 for the gearbox, 75W-90 for the differential, and several owners praising Motorcraft fluid in the six-speed; I did not read those threads, so treat them as leads.
Not covered yet
- Capacities and grades from Mazda, the NC and ND oil and filter parts, cabin filters, spark plug gaps, and coolant (see the NC coolant note).
- Owner accounts for the NC and ND on gear oil and oil choice.
© 2026 Fischer Interactive LLC. Written for the Ref Sensor app's Miata users. The seller's page is the authority.