biker349

hi,i've been researching this for over a week. posters on here recommend the ngk 1fr6q iridium plug. mercedes lists plug # 0041591403. i called bosch. they said the bosch fr7kpp33u was oem and it crossed referenced to the mercedes #. they also said that the bosch was extremely similar to the ngk in performance and longevity. mercedes lists the plug for $17.30. i called 4 dealers and no one could verify the mfg. the only clue i got from one was that it listed the mfg. in germany. both plugs list on line for about $21.00, but in reality the bosch is about $5.60 and ngk about $10.00. the majority of online places list bosch as oem, but there are a few exceptions that list ngk. so, does anyone know definitively if bosch, or ngk is oem? am i splitting hairs and spinning my wheels? is there really much difference? i already ordered the bosch based on my somewhat inconclusive research, but am having second thoughts. so can anyone give me some advice and peace of mind?
thanks and sorry for rambling.

awiner

My 2003 CL55 had NGK as OEM.

The Bosch plug for your 04 CL600 is part # FR-7-KPP-33U+

Either the NGK IFR6Q-G Bosch FR-7-KPP-33U+ are fine and I wouldn't worry much about one brand vs the other.