Bruce ,

The new replacement plugs from the factory are double platinum for the turbo's and triple electrode for the non-turbo. One of the reasons for this is the ability of the engine ECU to detect missfires. If a plug loads up and missfires for more than a couple of cycles, a misfire code is stored and the

"check engine" light will come on. Whatever plugs you buy , just keep this in the back of your head.

Ted

Stillman Volvo