Upgrading to Iridium Spark Plugs?
Thread Starter
Junior Member
Joined: Aug 2016
Posts: 18
Likes: 1
2006 C350 4MATIC
Upgrading to Iridium Spark Plugs?
Hi MBWorld,
I have a 2006 C350 with the M272 3.5L V6 engine that I was looking to do a tune up for. I plan on changing the spark plugs, ignition coils (they've been the same ones for the last 4 years I've owned the car), new air filters, MAF cleaning, and an oil change.
I know the owners manual recommends the Bosch/NGK Platinum spark plugs, but is there any issue with upgrading to Iridium plugs? I say "upgrade" because it's my understanding that Iridium plugs have better performance and a more complete combustion. I assume this would translate into slightly better fuel economy and power. I've driven myself absolutely neurotic researching about this for hours upon hours, but it seems there's not too much information regarding the application of Iridium spark plugs in our M272 engines.
There are my options:
1. (OEM): NGK 4288 PLKR7A Laser Platinum
2. NGK 93911 LKR7AIX Iridium IX
3. Denso 5353 IXUH22 Iridium (These are boasted as being 'performance' spark plugs, having the .4mm center electrode)
I also note that the Laser Platinum plugs have a resistance of 1000 ohms vs. the Iridiums which have a resistance of 5000 ohms. Does this matter at all?
Thanks so much for the help.
I have a 2006 C350 with the M272 3.5L V6 engine that I was looking to do a tune up for. I plan on changing the spark plugs, ignition coils (they've been the same ones for the last 4 years I've owned the car), new air filters, MAF cleaning, and an oil change.
I know the owners manual recommends the Bosch/NGK Platinum spark plugs, but is there any issue with upgrading to Iridium plugs? I say "upgrade" because it's my understanding that Iridium plugs have better performance and a more complete combustion. I assume this would translate into slightly better fuel economy and power. I've driven myself absolutely neurotic researching about this for hours upon hours, but it seems there's not too much information regarding the application of Iridium spark plugs in our M272 engines.
There are my options:
1. (OEM): NGK 4288 PLKR7A Laser Platinum
2. NGK 93911 LKR7AIX Iridium IX
3. Denso 5353 IXUH22 Iridium (These are boasted as being 'performance' spark plugs, having the .4mm center electrode)
I also note that the Laser Platinum plugs have a resistance of 1000 ohms vs. the Iridiums which have a resistance of 5000 ohms. Does this matter at all?
Thanks so much for the help.
MBWorld Fanatic!
Joined: May 2017
Posts: 2,290
Likes: 434
C320
Resistors in spark plugs exist to block ignition noise from messing with the car's electronics. To little resistance and you'll run into weird electronic symptoms like noise on the radio or even stalling. Too much resistance and your coils might not be powerful enough to fire the plugs causing misfires, loss of power at high load and CEL. The coils were designed to work with a specific plug. Use that plug. Just because a different plug is more expensive of promises some kind of ill defined performance improvement doesn't make it an upgrade.
Thread Starter
Junior Member
Joined: Aug 2016
Posts: 18
Likes: 1
2006 C350 4MATIC
Resistors in spark plugs exist to block ignition noise from messing with the car's electronics. To little resistance and you'll run into weird electronic symptoms like noise on the radio or even stalling. Too much resistance and your coils might not be powerful enough to fire the plugs causing misfires, loss of power at high load and CEL. The coils were designed to work with a specific plug. Use that plug. Just because a different plug is more expensive of promises some kind of ill defined performance improvement doesn't make it an upgrade.
Newbie
Joined: May 2021
Posts: 5
Likes: 2
From: Gainesville Fl
2003 S55 AMG
Do not use the general platinum plug. Use the one that is the original equipment plug usually Bosch. The gimmick platinums will cost half as much as the true plug. MB also recommends phasing the plugs. That means that the electrode must be pointed the proper direction within the cylinder. Coils don’t need replacing till they fail. They do not have a planned maintenance cycle. The plugs are recommended to be replaced every 60,000 miles or five years. Don’t waste your money. You can not get any better performance than with the OE plug.
