[W126 Coupe] Spark Plugs

[GreyGarageRuss at aol.com]

I recently called my local Benz dealer to ask if he had and Bosch W9DCO  
plugs for my 1988 560 SEC and he said he did.  When I went to pick them up  he 
handed me WR9DC+ plugs. His computer screen indicated that  W9DCO'S were Bosch 
#003-159-10-03, the same number on the box of  WR9DC+ plugs.  I didn't take them 
and when I got home, I checked one of the  old plugs in my 560.  It was a 
WR9DC+.  Apparently the t shop that put  in these plugs when I bought the car 3-4 
years ago, used these resister  ones.
My question now, is what is the difference....will anything be  
harmed...should I change them immediately or stick with this type?  The car  runs very well 
as is but I want to do the right thing while I am going to put  new wires on.
Thanks,
Russell
1988 560 SEC



   
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