I know this is a really old thread, but it was the only thing on the forum dealing with this type of spark plug.

My car, an 89 300se had platinum plugs when I bought it. I switched them out right away for the only copper core plugs I could find locally, which were resistor Champions. I then ordered a set of non-resistor Bosch plugs, but when they arrived the supplier had substituted resistor plugs. I contacted them but they claimed the non-resistor Bosch plugs were no longer being made and these were all that he or anyone else could get. I finally decided to return them for a refund and just leave the Champions in place.

A year and half later the Champions were worn out, so I tried again to find some non-resistor plugs and wound up ordering a set of non-resistor NGKs. However, when they arrived they had been substituted for resistor plugs. Called the supplier and got the same story. I wasn't sure I believed them but I returned the the plugs for a refund.

I've been reading about the Nology Silverstone, silver core, non-resistor plugs for awhile now. There was nothing about them on the forum but there is smattering of opinion on the web, some good, some bad. Anyway, I decided to be the guinea pig and give them a try.

I gapped them at .035 and they've been in about a week. The idle, which with the worn out Champions had gotten a bit rough is now smooth, though I don't think it's any smoother than it was when the Champions were new.

I guess we'll see how it goes. The Champions lasted about 35,000 miles. I'll report on the Silverstone's performance from time to time, and see if I think they were worth the $7 per plug premium over the price of the Champions. At least I finally have some non-resistor plugs in there.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire