# TR5IX NGK Iridium Spark Plug | Genuine NGK Spark Plug

## 🔧 Product Description

**NGK Iridium Spark Plug – Part Number: TR5IX**

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: 7397
-   Thread: 14 mm
-   Reach: .708"
-   Hex: 16 mm (5/8 in)
-   Seat: Tapered
-   Terminal: Solid
-   Type: Projected

## 🚘 Application

Listed in NGK's application charts for marine, motorcycle, ATV and snowmobile equipment and automotive vehicles. The gap is not the same on all of them – the chart lists between 0.5 mm and 1.0 mm depending on the engine, so check the line for yours.

-   Crusader CLASSIC-5.7L PLUS EFI – Inboard Engine
-   Crusader CLASSIC-5.7L PLUS MPI – Inboard Engine
-   Crusader CLASSIC-7.4L MPI – Inboard Engine
-   Crusader PLATINUM-5.7L PLUS MPI – Inboard Engine
-   Crusader PLATINUM-7.4L MPI – Inboard Engine
-   Indmar 5.7L V8 EXCEPT LS1 (8 CYL GM SMALL BLOCK, 2005-1994) – Inboard Engine
-   Indmar 7.4L V8 (8 CYL GM BIG BLOCK, 2005-2003) – Inboard Engine
-   Indmar 8.2L V8 (8 CYL GM BIG BLOCK, 2005-2003) – Inboard Engine
-   Kodiak 5.7L V8 310 HP (350 CID, 2000-1999) – Inboard Engine
-   Marine Power GM V6 4.3L (262 CID, 2000-1998) – Inboard Engine
-   Marine Power V8 5.0L (305 CID, 2000) – Inboard Engine
-   Marine Power V8 5.7L (350 CID, 2000-1998) – Inboard Engine
-   Mercruiser 3.0L MPI ECT (4 CYL GM) – Inboard Engine
-   Mercruiser 4.3L TKS (6 CYL GM V-6) – Inboard Engine
-   Mercruiser 350 MAG MPI (8 CYL GM SMALL BLOCK, FROM 0L304700, 2006-2000) – Inboard Engine
-   Mercruiser 350 MAG MPI GEN+ HORIZON (8 CYL GM SMALL BLOCK, 0L304700 TO 0M309999) – Inboard Engine
-   Mercruiser BLACK SCORPION MX 6.2 (8 CYL GM SMALL BLOCK, 2006-2000) – Inboard Engine
-   Omc 2.3L COBRA (1990-1987) – Inboard Engine
-   Omc 3.0L COBRA (1998-1993) – Inboard Engine
-   Omc 3.0L COBRA HO (1998-1990) – Inboard Engine
-   Omc 5.0L COBRA EFI (1995-1993) – Inboard Engine
-   Omc 5.8L COBRA EFI (1996-1992) – Inboard Engine
-   Omc 5.8L KING COBRA EFI HO (1995-1993) – Inboard Engine
-   Volvo-Penta OCEAN SERIES - 4.3L OSI-XPD – Inboard Engine
-   Volvo-Penta OCEAN SERIES - 5.0L OSI-XPD – Inboard Engine

That is the 25 most common of 244 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.

-   ACDelco: 12571533, 1835350T, 1835384T, 1835422T, 241-904, 241-906, 241-910, 25164640 and 8 more
-   Champion: 7408, 9204, 9204-2, 9204S, 9405, 9405-2, 9602, 9808 and 8 more
-   Bosch: 4011, 4205, 4211, 9602, 9657, H8DP, HR8D1133X, HR8DPX and 2 more
-   Autolite: XP103, XP103DP2, XP104, XP104DP2, XP105, XP105DP2, XP106, XP5243
-   DENSO: 4713, 5090, 5325, IT16, IT16TT, ZTJ16R10
-   Motorcraft: AGSF22PP, AGSF32W, AWSF22E
-   Beck Arnley: 1765290

## 📦 Condition

-   Brand new genuine product
-   Supplied in original packaging

## Details

- **Price:** 40.0 AUD
- **Vendor:** NGK
- **Type:** Ignition & Controls

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 40.00 AUD | In stock |

## Images

- TR5IX NGK iridium spark plug
- TR5IX NGK iridium spark plug firing end

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/tr5ix-ngk-iridium-spark-plug-genuine-ngk-spark-plug)
> Updated: 2026-09-03