1990 MB 300E Bosch Spark Plug Question
 

Hi,

I have a 1990 MB 300E and have Bosch HR9DC+ (#7978) Spark Plugs currently installed in my car. I received a couple of boxes of Bosch HR9DC (#7578) and was wondering if it was ok to use these for my next tune up? What is the difference between the two?

It seems that they might be old stock.....I am just guessing because they are not "+".

Any information would be greatly appreciated!

Bob

Do a search. This is probably one of the MOST discussed (to death) topics on this board.

tp,

I did a search and spent much time sifting through the resistor/non resistor issue. I had trouble finding the answer to my specific question about these two resistor plugs so I took the easy way out and addressed the forum. I will keep reading threads I am sure you are right it's there.

Thanks
Bob

R is the resistor plug. No go.

...

Ok I am convinced.........get rid of the resistor plugs! The car was running fine using them so I RESISTED (forgive me) the quest to find non resistor plugs. It looks like the NGK (BP5EFS) sparks are a good replacement for the Bosch.

Does anyone have a good source for the NGK or equivalent replacement?

Thanks again.

The MBUSA Classic Center in Irvine stocks the correct non-resistor NGK plugs. Last time I checked, Fastlane Phil did not.

http://www.mbusa.com/mercedes/MBHome.html#/onlymbMenu/classicCenter/