Here is a list of suitable replacement bulbs for a 1990 Mk1 car.
Headlights Dip /Main beam H4. 60/55 watt. Base description P43t Type description; H4
Sidelights front RW501 5 watt Base description W2.1x9.5d Type description W5W
Front Indicator RW382 21 watt.Base description: BA15s Type description; P21W
Rear stop and tail RW380 21/5 watt…Base description: BAY15d Type description; P21/5W
Rear indicator RW382 21 watt…Base description: BA15s Type description; P21W
3rd brake light bulb 681593 HAL BULB HBU955 16W [Halfords]
Fog light RW382 21 watt.Base description: BA15s Type description; P21WNumber plate 2 X wedge base all glass RW501 5 watt.Base description W2.1x9.5d Type description W5W [For Roadsters Halfords Ref HBU207. This reference ties into bulb type 382. 15mm bayonet with directly opposed pins.]
Interior lights 2 x Festoon Code: R261 S7d Thin Festoon 8 X 26
Ash tray capless RW284 2.3 watt.?????
Heater panel 2 x capless RW286 1.2 watt (the originals are slightly bigger dealer only but RW286 fits OK) .Base description W2x4.6d / size 18x5mm
Hazard switch 12 volt 65mA wired sub minature bulb (Maplins part No PG 78K which is red)
Headlight retract switch 12 volt 65mA wired sub minature bulb (Maplins part No PG77J which is clear)
Instruments capless RW504 3 watt.Base description W2.1x9.5d note this is same size as 5 watt wedge
Warning lights capless RW286 1.2 watt..Base description W2x4.6d / size 18x5mm
The instrument panel bulbs consist of 4 green RW504 bulb holders they light the gauges, the bulbs have a green coloured rubber sleeve fitted this should be carefully removed and fitted to any replacement bulbs, incidentally these bulbs can be changed for coloured LED`s if you fancy a change of colour.
There are 3 black RW504 bulb holders these are plain bulbs 2 for L/R indicator lights and 1 for main beam indicator.
There are 5 RW286 bulbs which are for charge light, brake warning light, fog light and hazard warning and headlight retractor function.
The RW part numbers are Ring Automotive bulbs which should be widely available.
Bulb List Mazda MX5 2.5
| Location | Voltage/Wattage | Colour/Qty | Type |
| Headlamp Dipped Beam | 12 volt 55 Watts | Clear x 2 | HB4* |
| Headlamp Main Beam | 12 volt 60 Watts | Clear x 2 | HB3 |
| Sidelight (front) | 12 volt 5 Watt Capless | Clear x 2 | 501 |
| Indicator (front) | 12 volt 21 Watts | Amber x 2 | 581 |
| Indicator (side) | 12 volt 5 Watts Capless | Clear* x 2 | 501 |
| Interior | 12 volt 5 Watt Festoon 30 mm | Clear x 1 | 269 |
| High Level Brake Light | 12 volt 21 Watts | Clear x 1 | 382 |
| Number Plate/Boot Light | 12 volt 5 Watts Capless | Clear x 2 | 501 |
| Stop & Tail | 12 volt 21/5 Watts Capless | Clear x 2 | 580 |
| Reverse Light | 12 volt 21 Watts Capless | Clear x 1 | 582 |
| Fog Light | 12 volt 21 watts Capless | Clear x 1 | 582 |
| Indicator Rear | 12 volt 21 Watts Capless | Amber x 2 | 582A |
* Headlamp HB4 dipped bulbs were replaced in 2003 by (H7?) 55 Watt bulbs (from VIN numbers 413680)