1989 560sec 6.0L AMG & Renntech
Quick question: what spark plugs do you recommend I put in my '92 600sel? Some people say NGK, some say stick to copper. What do you suggest? I searched a bit but I just found a bunch of posts from people with the 6 cyl W140s (not bashing the 6 cyls but I have the 12 and I don't want to do anything to harm it). Another person said that the iridium plugs can make my engine run poorly? Any insight into this mess?