Spark Plugs Question

[JDoggery]

I was looking in what the manual says for plugs and it states:
Bosch F 7 KTCR
0.039 in (1.0 mm)

Anyways, my question is what material are these made out of, and is there a better plug for this engine? What about wires? Are there better ones than stock? What are the benefits?

Also, the service booklet says that the 111 ML engine needs to have these changed at approx. every 30k miles or 4 years, is this correct, or what have you guys done? Any help would be greatly appreciated. Thanks.

Car is 99 c230.

[Metromoto202]

i would change them out every 30k, and your belts.

[Josh R]

Its best to use a copper plug from Bosch. Platinum plugs for SC cars are a no no. Platinum plugs are used for broad climates, therefore their heat range is very broad. A copper plug on the other hand has a more specific heat range, also it prevents detonation much better. If you have done mods to your car its best that you cross reference your original plug to copper and go 1 heat range colder. Rule of thumb is "The hotter the motor the colder the plug". Hotter meaning high performance.

[Linh]

Platinum plugs for SC cars are a no no.