Spark Plug & Ignition Tools: what Claude and GPT would buy

Two AI models chose on their own, with no web access. Nobody tested these products: this is what each one says, and how to check it.

They disagree: Claude chooses TEKTON and GPT chooses GEARWRENCH

In Automotive, Claude and GPT choose the same brand in 60 of 112 categories.

Claude Opus 5.5 · October 27, 2026

TEKTON (brand)

Makes well-made spark plug sockets with retention that holds the plug, plus extensions for deep plug wells.

Not for: Shops that need specialty coil pullers or ignition scopes.

GPT 6.1 Sol · November 10, 2026

GEARWRENCH 80546

Its magnetic retention, swivel joint, and extended reach make removing and installing spark plugs in tight wells easier.

Not for: Spark plugs requiring socket sizes other than 5/8 inch.

Claude also lists GEARWRENCH among the brands that matter.

Hex size. Match the plug hex; common sizes are 5/8 in, 13/16 in and 14 mm. Different engines use different plug hex sizes.
Plug retention. Use a rubber insert or magnet to grip the plug. It lets you lift the plug out of deep wells without dropping it.
Gapping fine-wire plugs. Use a wire-style gauge, not a coin or ramp gapper, on iridium and platinum plugs. Coin gappers can bend or crack the fine center electrode.
Thin-wall sockets. Use a thin-wall socket for narrow plug tubes. Standard sockets bind in deep, narrow wells.

Shops seen in search results on November 5, 2026. A shop missing here may sell it too. Nothing was checked by a person.