# XR4IX NGK Iridium Spark Plug | Genuine NGK Spark Plug

## 🔧 Product Description

**NGK Iridium Spark Plug – Part Number: XR4IX**

Iridium NGK spark plugs offer a longer service life than a standard nickel-tipped spark plug: while nickel-alloy plugs offer a service life of roughly 20,000-40,000km, NGK Iridium IX spark plugs offer a service life of up to 60,000km, so fewer replacements are needed over time despite the higher initial cost.

Precious-metal spark plugs like the NGK Iridium IX also offer higher ignitability, achieved with an exposed fine-tip centre electrode that promotes superior flame growth compared with a standard spark plug. Iridium has a much higher melting point (2410°C) than nickel (1453°C), allowing the centre electrode diameter to be reduced from 2.5mm to 0.6mm – a smaller electrode mass that reduces the impedance to flame progress, helping acceleration, fuel consumption and idle quality.

## ⚙️ Key Features

-   Fine iridium-tipped centre electrode for a slow wear rate and stable idle
-   Longer service life than standard nickel plugs
-   Trivalent metal plating provides superior anti-corrosion and anti-seizing properties
-   Corrugated ribs reduce the risk of flashover
-   Pure alumina silicate ceramic insulator, providing superior strength and better heat transfer
-   Copper core aids in heat removal
-   Triple seals prevent leakage

## 📏 Specifications

-   NGK stock number: 7189
-   Thread: 14 mm
-   Reach: 9.5 mm (3/8 in)
-   Hex: 20.8 mm (13/16 in)
-   Seat: Gasket
-   Terminal: Solid
-   Type: Projected

## 🚘 Application

Listed in NGK's application charts for marine, motorcycle, ATV and snowmobile equipment and automotive vehicles. The chart shows a 1.0 mm gap for these engines, but check it against your engine's manual before fitting.

-   Berkeley OLDSMOBILE (455 CID, 1976-1968) – Inboard Engine
-   Indmar OLDSMOBILE 5.7L V8 (350 CID, 1982-1976) – Inboard Engine
-   Indmar OLDSMOBILE 6.6L V8 (403 CID, 1982-1976) – Inboard Engine
-   Indmar OLDSMOBILE 7.5L V8 (455 CID, 1976-1975) – Inboard Engine
-   Buick Century (1958-1954) – 6-8 per engine
-   Buick Electra (1965-1959) – 6-8 per engine
-   Buick Gran Sport (1965) – 6-8 per engine
-   Buick Gran Sport (1967) – 6-8 per engine
-   Buick Invicta (1963-1959) – 6-8 per engine
-   Buick LeSabre (1965-1959) – 6-8 per engine
-   Buick Limited (1958) – 6-8 per engine
-   Buick Riviera (1965-1963) – 6-8 per engine
-   Buick Skylark (1954) – 6-8 per engine
-   Buick Skylark (1967-1965) – 6-8 per engine
-   Buick Special (1958-1951) – 6-8 per engine
-   Buick Special (1963-1962) – 6-8 per engine
-   Buick Special (1967-1965) – 6-8 per engine
-   Buick Sportwagon (1967-1965) – 6-8 per engine
-   Buick Super (1958-1951) – 6-8 per engine
-   Buick Wildcat (1965-1963) – 6-8 per engine
-   Cadillac Calais (1967) – 6-8 per engine
-   Cadillac DeVille (1967) – 6-8 per engine
-   Cadillac Eldorado (1967) – 6-8 per engine
-   Cadillac Fleetwood (1967) – 6-8 per engine
-   Cadillac Series 60 Fleetwood (1952-1950) – 6-8 per engine

That is the 25 most common of 126 applications NGK's charts list for this plug – ask us to check yours.

## 🔄 Supersession & Cross Reference

NGK's cross-reference tables list this plug against these part numbers.

-   Bosch: 4236, W10FC, WR9FP
-   Autolite: AP86

## 📦 Condition

-   Brand new genuine product
-   Supplied in original packaging

## Details

- **Price:** 58.0 AUD
- **Vendor:** NGK
- **Type:** Ignition & Controls

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 58.00 AUD | In stock |

## Images

- XR4IX NGK iridium spark plug

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/xr4ix-ngk-iridium-spark-plug-genuine-ngk-spark-plug)
> Updated: 2026-09-03