2012 e550 NGK’s?
Stock Bosch number is different for your V8 so I don't think those NGK are correct for your car. Unfortunately I don't know which NGK are applicable, perhaps a 550 owner will have info.




LKR7AIX for $8.99
PLKR7A for $13.99
LKR7BGP-8 for $4.69
The middle one is what I got from AutoZone. They are kind of expensive for a spark plug but NGK plugs in my opinion are the best you can get. I'm sure other plugs work too but Mercedes also had these plugs in my car from the factory.
The last on the list is not available by AutoZone net site. Don't know why they even list it.
My concern in this case is that the oem Bosch numbers are different for E350 and E550, leading me to believe that heat range or plug indexing/reach into the combustion zone may be different. The PLKR7A are listed by a variety of vendors as fit for the E350 but I'm just not sure about the 550.




My concern in this case is that the oem Bosch numbers are different for E350 and E550, leading me to believe that heat range or plug indexing/reach into the combustion zone may be different. The PLKR7A are listed by a variety of vendors as fit for the E350 but I'm just not sure about the 550.
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I had always thought that plug indexing was limited to hi performance or race cars but I found his info enlightening. I'll see if I can find it somewhere.
I'm not saying that the engine wouldn't run but from the info I saw MB went to great lengths to ensure the electrode was in a particular position within the combustion chamber.
For all I know it may be the same with these NGK plugs, but again I hesitate about the different part numbers for oem plugs between V6 and V8.
EDIT - Arrie, you may be correct for the non-direct vehicles. Here's the post about it, as related to direct injection:
https://mbworld.org/forums/e-class-w...zing-fact.html
Apologies for posting before verifying

However, the nagging part to me is still on the oem part number difference between V6 and V8, may be related to depth of threads and heat range.
May seem like splitting hairs but after seeing several engines with piston "pings" from wrong heat range of plugs (too high) it may worth a second look.
Last edited by Mud; May 6, 2019 at 11:49 AM.
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