I want to replace the spark plugs the car has 60k miles on the origianl plugs. Does anyone have any experince with after market such as Bosch Paltinum 4. Any reccommendations for a specific brand or should I get the originals from AC Delco.

 

I always stay with the AC Delco factory spec plugs.That's what your Northstar left the factory with and they have given you 60,000 miles of service and they were designed for your engine. I paid $122 for 8 from the GM parts supplier last time I changed them.

 

listen to Katz above,
additionally, you want DUAL platinum, not just platinum - DUAL PLATINUM .
BTW, why are you changing them at 60kmiles? arent those good for 100kmiles?

howver, funny you bring this up, i posted this earleir today:
https://www.cadillacforum.com/m_6032/tm.htm





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Car seems to havelost some pep. Also gas mileage is down to the mid 18 range. was always around mid 19 to 20 mpg,