How to use this appendix
Use this as a pre-service shopping sheet for Mazda MX-5 NB (1998-2005). It is designed to eliminate vague “use correct fluid” instructions.
- Buy by capacity + safety margin (don’t buy exact-to-the-mL amounts).
- Match fluid spec first, then brand.
- If chemistry/spec is unknown in the car, do a full change rather than top-up guesswork.
NB fluid/spec table (practical workshop baseline)
| System | Spec to target | Typical service amount | What to buy |
|---|---|---|---|
| Engine coolant | Ethylene-glycol, aluminum-safe. NB commonly accepts traditional or OAT coolant if not mixed. FL22 only if cap/manual/label requires it. | ~6.0 L total system | 7 L premix or 4 L concentrate + 4 L distilled water |
| Engine oil + filter | API SL/SM+ quality oil. 5W-30 is common NB baseline (adjust by climate/engine wear). | ~3.6 L (3.8 US qt) with filter | 5 L jug + filter + crush washer |
| Manual transmission | GL-4 75W-90 for synchronized NB gearbox (avoid generic GL-5 here unless explicitly synchro-safe by manufacturer data). | ~1.8-2.0 L | 3 x 1 L / 3 qt |
| Differential | Hypoid GL-5 75W-90 (open diff and most stock NB LSD setups). | ~0.6-0.8 L | 1 x 1 L / 1 qt |
| Brake system | DOT grade on reservoir cap/manual (DOT 4 commonly used on NB service). | ~0.7-1.0 L full flush | 1 L sealed bottle |
| Clutch hydraulic | Same DOT family as brake fluid. | ~0.2-0.3 L clutch-only bleed | If doing brakes too: one fresh 1 L bottle total |
| Power steering | ATF with Dexron II/III compatibility (NB manual-language references: Mazda M-III equivalent). | ~0.7-0.9 L full exchange | 1 L ATF |
| Shifter turret (manual cars) | Gear oil for turret service per your transmission setup (commonly GL-4 style MTF in NB owner practice). | ~90-100 mL | Small bottle / use measured remainder |
Known-good product examples (non-sponsored)
Coolant (NA/NB-compatible chemistry choices)
- Comma Super Coldmaster (traditional ethylene-glycol)
- Comma Xstream G30 (OAT long-life)
- Mazda FL22 premix only where explicitly specified on your car
Manual transmission (GL-4)
- Red Line MT-90 (75W-90 GL-4)
- Other reputable GL-4 75W-90 MTF products that explicitly mention synchronized manual boxes
Differential (GL-5)
- Red Line 75W90 GL-5
- Motul Gear 300 75W-90 (GL-4/GL-5; acceptable where your diff requires GL-5 behavior)
Power steering ATF
- Dexron III/Mercon labeled ATF from major brands
- Multi-vehicle ATF explicitly listing Dexron II/III compatibility
Consumables to keep on the shelf
- Engine sump plug crush washers
- Differential/trans plug washers
- Distilled water (5 L minimum)
- Brake cleaner
- Nitrile gloves
- Spill-free coolant funnel
- Fluid transfer pump for side-fill gearboxes/differentials
- Marking pen + service labels
Record this every time (high value for diagnostics)
- Date + odometer
- Exact product name and viscosity/spec line from bottle
- Quantity used
- Any contamination notes (metallic, milky, burnt smell)
- Next planned interval
Good records make later diagnosis of shift feel, diff whine, cooling behavior, or PS noise dramatically easier.
Sources
- BOFI Racing — What Coolant Do I Need For My MX-5? (NB coolant chemistry options and 6 L capacity planning). Retrieved 2026-03-14. https://bofiracing.com/blog/what-coolant-for-my-mx-5/
- BOFI Racing — What Gearbox and Differential Oil Should I Use in My MX-5? (NB GL-4 gearbox / GL-5 diff guidance and practical capacity planning). Retrieved 2026-03-14. https://bofiracing.com/blog/what-gearbox-and-differential-oil-should-i-use-in-my-mx5/
- Miata.net Forum — [NB] Castrol Transmax Import ATF for power steering? (owner-cited manual language: Mazda M-III equivalent / Dexron II context). Retrieved 2026-03-14. https://forum.miata.net/vb/showthread.php?t=549067
- MELLENS — Mazda Miata Factory Service Manual archive (year/VIN-level confirmation source). Retrieved 2026-03-14. https://www.mellens.net/mazda/