Aftermarket Bosch Plugs vs. Plugs from MB dealer.

[Trav]

The plugs are not very accessible.

View attachment 107047
View attachment 107046

(The plugs are on the “underside” of the cam cover, and at an angle.)

I suppose I could have marked the plug-to-socket orientation for both plugs, but the car works fine for now.

That was my thought, it is rare you can even see down the plug holes on some of these cars. Still a PITA job.

 

[FordMan59]

I've had people tell me Bosch plugs didn't work well in Ford engines. I've used Bosch Platinum plugs in my Fords for years with most sets lasting in excess of 100K miles and were only changed then because I felt guilty they'd been in so long.

 

[Trav]

Indexing can change where the spark is directed inside the combustion chamber and make a difference in how the engine runs.

My Mercedes both use NGK plugs.

If the OP‘s car were mine, I would go with genuine MB in this case.

People who have run Bosch in their M275s have regretted it.

The MB engines that require indexing washers should never use NGK plugs. Personally I would buy OE from a dealer also.
A couple of years ago I lost the coil pack on my Viggen, I put new NGK plugs and new NGK coil pack, In 1st gear give it some revs and it would break down. I put OE plugs in and it was a little better, put a new OE coil pack in ( more $$) and that cured it. Ironically OE was also made by NGK,
The only difference I could see is the OE was made in Japan the aftermarket not.

https://techtips.alleuro.com/wp-content/uploads/2020/02/mercedes-spark-plug-index.pdf

 

[Astro14]

My engine (same in both cars) doesn’t require indexing, fortunately, and genuinely runs well on real (not fake) NGK iridium plugs.

However, that engine does require 24 of those iridium plugs, so a plug change is an all day affair…I’ve done it twice on the S600, and I’m about to do a plug change on the SL600.

 

[Trav]

If it doesnt require index plugs it is no issue, still 24 plugs can be a real PITA job.

 

[charles g]