NGK 90398 LMAR8E-J Standard Nickel Spark Plug 10mm

Vehicle Fitment

• No confirmed vehicle applications were found - NGK's own official product page states no automotive applications are associated with this part number, and no powersports application was confirmed either
• The unusually small 10mm thread size suggests this is likely a small-engine or specialty application rather than a standard passenger vehicle plug

Fitment Notes

• Verify exact engine compatibility using the plug's thread size, reach, and heat range specifications below, or by cross-referencing against your engine's OE spark plug number, before ordering

Features

• NGK Standard series construction, an OE cornerstone technology used for decades
• High-grade alumina silicate ceramic insulator provides strong dielectric performance and better heat transfer
• Triple gasket/seal design helps prevent combustion gas leakage
• Solid 98% pure copper core offers strong heat dissipation, conductivity, and a wide usable heat range
• Trivalent metal plating provides strong anti-corrosion and anti-seizing properties for easier installation and removal
• Corrugated ribs help prevent flashover
• Projected tip design

Specifications

• NGK stock number: 90398
• Service/OE number: LMAR8E-J
• Thread size: 10mm
• Reach: 1.040 in.
• Seat type: Gasket
• Tip design: Projected
• Resistor: Yes
• Electrode material: Nickel alloy
• Torque spec: 7.2-10.8 lb-ft (cast iron), 7.2-8.7 lb-ft (aluminum)

Included Components

• 1x Spark Plug

Product Description

The NGK 90398 (LMAR8E-J) is a Standard series nickel alloy spark plug, part of NGK's long-running "yellow box" lineup built as an OE-quality, reliable replacement plug. Its solid 98% pure copper core supports strong heat dissipation and conductivity across a wide operating range, while the high-grade alumina silicate ceramic insulator provides durable dielectric strength and improved heat transfer.

A triple gasket/seal design helps prevent combustion gas from leaking past the plug threads, and trivalent metal plating on the shell resists corrosion and seizing - useful for engines that don't see frequent plug changes. At just 10mm, the thread size here is notably smaller than what's typical for passenger car engines, which points toward a small-displacement or specialty engine application rather than mainstream automotive use.

Since no vehicle application data was available from NGK or any retailer checked, the safest way to confirm this is the right plug is to match its thread size, reach, and heat range against your engine's specification, or cross-reference your engine's existing OE spark plug part number directly.