The problem isn't the Platinum, it's the resistance. MB ignition systems use resistor-end plug wires. You have to be careful about resistor spark plugs, if the resistance gets too high (combination of resistor plug wire ends and resistor plugs) your spark can really start to degrade. If it gets too high, it won't fire worth a damn, and in wet weather secondary voltage could actually secure a path to ground that doesn't really include your electrode gap at all! I am fairly sure that Plat spark plugs on the market are all resistor plugs, I would feel confident about recommending Plat spark plugs if I knew they weren't resistor plugs. Seems an "R" in the plug number mears a resistor plug, never seen a Plat plug without an "R" in the plug number yet.....Gilly