I see that most of the posts regarding plugs seem to be about using factory Bosch. I also see that there is a NGK copper core plug as an alternative. I have had great luck with NGK in non MB applications.

What is the feeling out there about using a NGK copper core plug in an SL500?

Just make sure it is a non resistor plug and you should be good to go.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Spark plug brands are just like car brands..if YOU like them & they work...go for it!

There are at least 5 different plugs that will FIT most engines but why not use the ones designed for the engine?

For Toyota use Denso..For Ford use Motorcraft & GM use AC & for ALMOST all MB's use Bosch.

I'm sure that many will post HOW much better their brand IS..

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

No argument here, as I subscribe to the same principal.
A point of note is, that on many occasions, switching from one brand to another is NOT a direct cross-reference, although a catalog may suggest so.

__________________
2007 C 230 Sport.

Can't go wrong with either.

__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

I agree with Doc and Manny, but if you own an MB with a 103 motor, you're now faced with a dilemna.

Bosch has stopped making the H9DC and H9DCO non-resistor plug. They now make a similar number with an "R" or resistor designation in the naming scheme. I think it's H9RDC - something like that.

I tried almost 3 months ago to order the Beru equivalent to the Bosch H9DC and H9DCO from kingsborne.com and have yet to receive them. In my last email correspondence with the owner, I was told the plugs were still in Germany. That was a month ago. Two weeks ago I emailed him with a request for status update and have not heard from him.

So.....it looks like I'll be hunting for anyone's version of a non-resistor H9DC/H9DCO plug soon.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

Any recommendations from the dealer?

__________________
2012 E350 Bluetech