[Bilbofraggins]

I’ll be staying with Bosch plugs…when I change in 25000 Km or likely more….If I was in Dubai - or another hot region then maybe I’d try the NGK - with meticulous gap conformity; but I’m in Canada…

Personally, too many down sides, and not worth the risk with colder plugs in the S63 - outweighing the potential benefit for me… although the NGK 97506 (SILZKBR8D8S) is standard in my sons 2015 X3 with the N20.

“Cons of Colder Spark Plugs

While colder spark plugs offer several benefits, they also come with some potential drawbacks. Here are some of the cons of using colder spark plugs:

Potential Misfires

Colder spark plugs can be more prone to misfires, especially if they’re not installed correctly or if the engine is not tuned properly. Misfires can cause damage to your engine and can be expensive to repair.

Cold Starting Issues

Colder spark plugs can also cause cold starting issues, especially in colder weather. This is because the colder temperature of the plug can make it more difficult to create a spark, which can make it harder to start the engine.

Risk of Engine Damage

If colder spark plugs are not installed correctly or if they’re not appropriate for your engine, they can cause damage to your engine. This is because the colder temperature of the plug can cause detonation, which can damage your engine’s pistons, cylinder walls, and valves.”