NGK Spark plug equivalent to OEM
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From: Colorado
G550
About 20 years ago, I changed out NGK plugs in a Nissan Xterra with a Bosch plug that cross referenced as a direct replacement. My mileage plunged noticeably to 16 mpg from around 20. I replaced the Bosch plugs with a new set of NGKs, and fuel economy was restored. Since then, I've never strayed from OE spec sparkplugs.
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
That's interesting, my flex-fuel car came with NGK's and my non-flex fuel cars came with Bosch plugs, Different part numbers entirely, Bosch does make plugs for flex-fuel cars, but they are a different part number than the plugs for non-flex-fuel cars
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
different connector ends
I also have an engine like yours, but mine is built for flex fuel. However, according to the EPC, both car engines (flex and non-flex) use the same plugs (A0041596903). I just found in my particular case, the NGKs indexed better than the Bosch plugs.
I had gotten the Bosch plugs from FCP Euro and actually returned them as defective because they would not all index within limits.
I had gotten the Bosch plugs from FCP Euro and actually returned them as defective because they would not all index within limits.
flat connection end
We'd like to upgrade non-flex fuel Bosch plugs to NGK but MB made that more difficult by using a different style connection for flex-fuel plugs.
In addition they also use different coils, not just matching boot connectors.
That is a lot of variables to sort out:
plug physical size
plug temperature range
matching boots connectors
(new coils ?)
It would be special if we could X-Ref the NGK drop in upgrade for MB/Bosch...
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MB’s of all kinds.
For me, it’s all about FCP Euro or going to the dealership and getting them from the parts counter. I’m not running the risk to save a few dollars. FCP carries NKG and I have used them before with no issues. I just refuse to buy this type of stuff from eBay or Amazon.
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Joined: Dec 2025
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From: Sydney, Australia
W213 2017 E400
Excellent choice. Those are the plugs (NGK) I use in my M276 3.0L turbo. I also buy mine from RockAuto. I didn’t know they ship overseas. Interestingly, my M276 3.5L non-turbo uses different plugs (Bosch). But that engine is also built for flex fuel, so I don’t know if that makes a difference.
. I just learning that MB requires spark plug indexing. Did you do this when you install yours ?
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
indexed by manufacturing
The plugs are manufactured to index in the related engine heads.
The GND straps are welded in relation to the threads so nothing more needs to be done. You can inspects the exact strap locations.
The GND straps are welded in relation to the threads so nothing more needs to be done. You can inspects the exact strap locations.
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@PotatoHeadII Got from RockAuto today... very fast shipping . I just learning that MB requires spark plug indexing. Did you do this when you install yours ?
. I just learning that MB requires spark plug indexing. Did you do this when you install yours ?See attached
Last edited by PotatoHeadII; Mar 31, 2026 at 04:15 AM.
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From: Fleriduh
W212 E63S Wagon - GSL580 - E63 - E350 - C300
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
You can mark them before installation, then you'll know for sure, When I did mine on my '13 flex-fuel at 60k, I used MB OEM NGK's and they indexed in spec
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From: Australia
W213 e300 MY19 (Aus market)
Sorry, I don't have them to show you as I am looking to buy those for my first time servicing my Merc (newbie). That is why I called NGK for the sparkplug suitable for my car.
I am looking around to buy them. Below are what I intend to buy
For SILZKFR8G7S (96427) SPARK PLUG - LASER IRIDIUM PREMIUM 96427 / SILZKFR8G7S | eBay Australia
For SILZKFR8D7S (95875) Genuine Set of 4 Spark Plugs For Mercedes-Benz CLA45 AMG GLA45 AMG NEW | eBay Australia
The second one above are superseded as per NGK. I think I am going to get the first one.
Do you think they are counterfeit ?
I am looking around to buy them. Below are what I intend to buy
For SILZKFR8G7S (96427) SPARK PLUG - LASER IRIDIUM PREMIUM 96427 / SILZKFR8G7S | eBay Australia
For SILZKFR8D7S (95875) Genuine Set of 4 Spark Plugs For Mercedes-Benz CLA45 AMG GLA45 AMG NEW | eBay Australia
The second one above are superseded as per NGK. I think I am going to get the first one.
Do you think they are counterfeit ?
For M264s SILZFR8F7S is the part number available in Aus. It seems we have not received the updated 7GS at the retailers here as yet.
https://www.sparkplugsdirect.com.au/...ug-silzkfr8f7s.
From the dealerships, each MB genuine plug costs about AUD70 retail. The NGK part is on sale here for $24.95. Your call.
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Joined: Dec 2025
Posts: 35
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From: Sydney, Australia
W213 2017 E400
Whatever you do, do not buy from eBay or Amazon - they are almost always counterfeit. Buy it from automotivesuperstore.com.au or sparkplugsdirect.com.au, they are genuine NGK retailers.
For M264s SILZFR8F7S is the part number available in Aus. It seems we have not received the updated 7GS at the retailers here as yet.
https://www.sparkplugsdirect.com.au/...ug-silzkfr8f7s.
From the dealerships, each MB genuine plug costs about AUD70 retail. The NGK part is on sale here for $24.95. Your call.
For M264s SILZFR8F7S is the part number available in Aus. It seems we have not received the updated 7GS at the retailers here as yet.
https://www.sparkplugsdirect.com.au/...ug-silzkfr8f7s.
From the dealerships, each MB genuine plug costs about AUD70 retail. The NGK part is on sale here for $24.95. Your call.
Yeah, you are right, neither Runautoparts or automotivesuperstore.com.au does have it. Unfortunately, Australia stock is very limited. So I ordered from RockAuto. It is reasonable price AUD$160 include shipping and super fast delivery (within 2 days, faster than domestic post).
Cheers
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
sparkplug... combustion VIP!
Interesting that the plugs shown in this case were for a Mercedes.
https://youtu.be/Hfl-1LbGu5s?si=kP0Moz-NorPnRyzK
https://youtu.be/Hfl-1LbGu5s?si=kP0Moz-NorPnRyzK
It's a collection of simple details.
Counterfeit is a no-brainer: don't mess up your engine with junk.
under gapping properly!
0.65 is the gap
dielectric lube application
plugs tell the combustion tale 👍
plug reading chart
- Buy genuine plugs only
- QA each plug carefully
- Gap plugs to your liking
- (don't drop them!)
The end goal is to have GREAT COMBUSTIONS far away from misfire chaos. It starts with timely ignitions.
Lean GDI mixtures are difficult to fire up.
### MY CHOICE GAP:
is what wizard references for boosted (or NA) engines.
.65mm is not so big it misfires towards EOL.
Wider gaps offer more lean penalties opportunities to enter misfire territories.
Last edited by CaliBenzDriver; Apr 4, 2026 at 05:26 PM.
Thread Starter
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Joined: Dec 2025
Posts: 35
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From: Sydney, Australia
W213 2017 E400
Just report back on this. A4 Service took me around 4 Hours. The sparkplugs process took me 2.5 hours, pulling the coils are just like a *****...
Apparently, my existing Mercedes sparkplug is NGK and also SILZKFR8G7S which is exactly what I bought from RockAuto
The indexing position of existing sparkplugs are
Cyl 1: 8 o'clock,
Cyl 2: 9 O'clock,
Cyl 3: 9 O'clock,
Cyl 4: 6 O'clock,
Cyl 5 : 7 O'clock
Cyl 6: 7 O'clock
It means even if dealer used OEM are not in the optimum range (10 O'clock - 2 O'clock) as per Mercedes suggested.
For my replacement sparkplugs
Cyl 1, 2 and 3 are 11, 11 and 3 O'clock respectively
Cyl 4, 5 and 6 are 4, 5 and 5 O'clock respectively.
Obviously, I torque the spark plug 23mN. However, when I try to experience with torque the old one to 25mN, it does not move the indexing even a minute. So over-torque a little WONT make any different in term of indexing.
Cyl 4, 5 and 6 indexing are bother me a little at time. But I decided to close the bonnet, wash engine bay, wash the car and call it the day.
May be it is better to get all indexing in the recommended range, but I since did not feel any different in term of engine run and driving, etc.
Thank you for all your help into my first Mercedes car service.
Apparently, my existing Mercedes sparkplug is NGK and also SILZKFR8G7S which is exactly what I bought from RockAuto
The indexing position of existing sparkplugs are
Cyl 1: 8 o'clock,
Cyl 2: 9 O'clock,
Cyl 3: 9 O'clock,
Cyl 4: 6 O'clock,
Cyl 5 : 7 O'clock
Cyl 6: 7 O'clock
It means even if dealer used OEM are not in the optimum range (10 O'clock - 2 O'clock) as per Mercedes suggested.
For my replacement sparkplugs
Cyl 1, 2 and 3 are 11, 11 and 3 O'clock respectively
Cyl 4, 5 and 6 are 4, 5 and 5 O'clock respectively.
Obviously, I torque the spark plug 23mN. However, when I try to experience with torque the old one to 25mN, it does not move the indexing even a minute. So over-torque a little WONT make any different in term of indexing.
Cyl 4, 5 and 6 indexing are bother me a little at time. But I decided to close the bonnet, wash engine bay, wash the car and call it the day.
May be it is better to get all indexing in the recommended range, but I since did not feel any different in term of engine run and driving, etc.
Thank you for all your help into my first Mercedes car service.
Last edited by spacemaster; Apr 21, 2026 at 09:59 AM.
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Posts: 118
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I had a similar problem when I tried Bosch plugs in my M276.8XX engine. The things would not all index properly. I returned the plugs to FCP Euro and got NGK plugs from RockAuto. They all indexed perfectly within the ± 45° range. Of course, I don't think you have FCP Euro or RockAuto there. Where did you buy your plugs? The dealer or elsewhere?
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From: Colorado
G550
After purchasing the MB (NGK) plugs that I mentioned in #13 above, I drilled and tapped a small piece of 3/4" thick PVC, and screwed each plug in finger tight. All 8 plugs seated with the same indexing to within just a couple degrees. From this, I concluded that if the engine cylinder heads are machined compatibly for indexing, that once torqued to spec, each plug should be where it needs to be. I don't know the configuration of each cylinder, but I'm assuming all have the same geometry regarding valves and injectors, so all plugs should torque to the same orientation. A quarter turn +/- seems to be within spec.
Thread Starter
Junior Member
Joined: Dec 2025
Posts: 35
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From: Sydney, Australia
W213 2017 E400
I had a similar problem when I tried Bosch plugs in my M276.8XX engine. The things would not all index properly. I returned the plugs to FCP Euro and got NGK plugs from RockAuto. They all indexed perfectly within the ± 45° range. Of course, I don't think you have FCP Euro or RockAuto there. Where did you buy your plugs? The dealer or elsewhere?
but happy to have them exactly the same part as Merc dealer
Thread Starter
Junior Member
Joined: Dec 2025
Posts: 35
Likes: 14
From: Sydney, Australia
W213 2017 E400
After purchasing the MB (NGK) plugs that I mentioned in #13 above, I drilled and tapped a small piece of 3/4" thick PVC, and screwed each plug in finger tight. All 8 plugs seated with the same indexing to within just a couple degrees. From this, I concluded that if the engine cylinder heads are machined compatibly for indexing, that once torqued to spec, each plug should be where it needs to be. I don't know the configuration of each cylinder, but I'm assuming all have the same geometry regarding valves and injectors, so all plugs should torque to the same orientation. A quarter turn +/- seems to be within spec.
for me, I found out that Dealer parts, torque to spec, and all perform by Dealer didn’t mean it will be correct.
also, torque more than 23mN abit does not affect anything in term of indexing.
but that is just me. I am happy with the run so far
