Autolite AP25 Spark Plug

Autolite Platinum Spark Plug AP25

Autolite Platinum Spark Plug AP25 is built for drivers who want OE-style ignition performance with added durability over standard copper plugs. It supports easier starts, quicker throttle response, and improved fuel economy while maintaining the form, fit, and function expected for a wide range of domestic applications.

Compatible With Chevrolet, Ford, GMC, Pontiac, Buick, Oldsmobile, Mercury, Dodge, Plymouth, and Lincoln vehicles across model years from 1967 through 1998, including applications such as Chevrolet C/K trucks, Ford F-Series, and GMC Safari/Sonoma. This part cross-references Champion Spark Plug 406 for the same application.

Key Features

• Platinum center electrode tip and core material for extended service life
• Nickel ground electrode tip with tapered design for stable ignition performance
• 0.044 in. pre-gap size for OE-style applications that call for this specification
• Resistor spark plug with 4,000 ohm resistance
• Ceramic insulator with mid-projection design for consistent combustion chamber exposure
• 14 mm thread diameter, 5/8 in. hex size, and tapered seat type
• OE-style replacement for many Chevrolet, Ford, and GMC ignition systems

Product Details

The Autolite Platinum Spark Plug line focuses on dependable daily driving performance with a platinum firing tip that helps resist wear over time. AP25 is an OE-style spark plug replacement for vehicles that specify a tapered-seat, mid-projection plug with a 0.044 inch gap. It is commonly selected for fitments such as 1996 Ford Bronco, 1996 Chevrolet Express 2500, 1996-1998 GMC Safari, and 1997 Ford F-250 HD, along with many earlier Chevrolet and GMC truck and van applications.

Autolite supplies ignition products for aftermarket and original equipment use, and this spark plug reflects that OE form, fit, and function approach. The AP25 part number is also a useful reference when searching for replacement spark plugs for Chevrolet P30, GMC P3500, and Ford E-Series applications.

Common Issues This Spark Plug Can Address

• Hard starting caused by worn spark plug electrodes
• Rough idle from inconsistent ignition firing
• Reduced throttle response from aged copper plugs
• Maintenance intervals shortened by rapid electrode wear
• Fuel economy loss related to weak or inefficient spark delivery

Installation Notes and Tips

Verify the vehicle’s required gap before installation and compare it to the listed 0.044 inch pre-gap. Confirm thread diameter, reach, seat type, and terminal style against the original plug specification before service. For fitment-based searches, AP25 is commonly referenced for 1980-1998 Chevrolet and GMC truck and van applications, 1980-1995 Ford truck and van applications, and selected 1980s-1990s Pontiac, Buick, Oldsmobile, Lincoln, Dodge, and Plymouth models.

When replacing plugs on Chevrolet C1500, Ford F-150, or GMC Sonoma applications, follow the vehicle service manual for torque and gap verification after installation.

Quality Assurance

Autolite manufactures platinum spark plugs to deliver greater durability than standard copper plugs while maintaining OE-style fit and function. The AP25 is built to meet the demands of a broad range of domestic ignition systems and is backed by Autolite’s long-standing role as a spark plug supplier for aftermarket and original equipment use.