Bosch Plugs
 

I need the best plugs for my 91 500SL. Bosch Platinum +4 or Bosch Super. What is the best between the two , or is there a better plug out there.

My opinion on plugs is to go with whatever mercedes puts in there from the factory.

Int he case of my 1992 300Ce, it has regular good ol copper core plugs (I think)

I know they aren't platinums, and I personally think my car runs great on the copper plugs.

Why change something like the plugs to a different kind if everything runs fine the way it is?

I would say go with the standard bosch plugs for you car. You should be able to order them from this site on the fastlane or partsshop.

Alon

Platinum plugs in M/B.....NOT!
A few short weeks after installing Platinum I took my car to the local independent M/B shop for rough idle (missing). We found it ;) , pulled out the platinum and put in the copper w 9 d's. Now she runs really nicely.

Platinum plugs post 94.
Copper plugs pre 95.
Don't even think about putting platinums in a W124. She won't like it;) In the SL i'd stick with the Bosch Super dco's.
Just my 2 cents......

Kevin,

At this point you may be wondering WHY NOT platinums.

There have been a mention or two of rumored catastrophic failure involving a platinum plug breaking and ruining an engine. I would think that the chance of this actually occurring would be remote.

The practical reason we use copper core plugs in the six cylinders is that the platinum plug has a very thin center electrode for cost saving reasons. This thin electrode produces a thin spark. The copper plug with its wide electrode produces a fat spark. In the sixes of this vintage, and I expect the V8's as well, the ignition system will not produce enough energy to give a smooth idle with the platinums.

Just thought you might like to know.

Have a great day,

LB is correct about spark energy not being enough in older ignition systems. Also, the platinum is a spin-off of racing technology. Racing involvles extended high speed runs at high temperatures in engines. At stop and go paces one will find the platinum has a tendency to 'load up' unless the ignition system is perfect, i.e. good wires, good cap and rotor, coil, etc...