I thought you shouldn't use anti sieze on spark plugs because the threads have a coating already applied to them.

 

For all 16 of my plugs I put a small amount of plug anti-sieze on the plugs the same as I have been doing the LS1 aluminum engine in my corvette.

 

It was recommended to me to not use it either. I didn't. German family who owns the dealership in st louis who sold it to me educated me about this.

 

Don't forget to replace your tensioner an idler pulleys when doing your serpentine. I replaced all at about 100k, it still looked like it was in great shape.

 

Do you need 8 or 16 plugs for the e550?

 

There are only 8 in an E550. The earlier E500 used 16 plugs.

 

I don't plan to change the spark plugs on my 2014 E550 ever, unless there is some detectable change in vehicle performance that might be attributable to faulty plugs. Factory manuals are written for the world, aim to protect the manufacturer, and are often biased more toward over-maintenance rather than under-maintenance. The M178 engine has a particularly vigorous spark generation system. That, coupled with very low average engine revolutions per mile should ensure exceptionally long spark plug life. I expect that someday spark plugs will be integrated into the cylinder head as a normally zero maintenance item.

 

I like that thought. Had the car 6 months now. Changed the oil to Mobil 1 0w 40
All the Filters too. Was thinking about the plugs since she has 87k on her. Don't know when it was done last. Has no problem so as said earlier. It ain't broke

 

never changing my spark plugs is the most outlandish thing i have ever heard.

 

These are the people who come back later and rip Mercedes all over these forums

 

I have a 2003 CLK 320 Coupe with 162,000 KM on it and just had the spark plugs changed. The plugs installed are the original ones from the factory. I installed Bosch Spark Plugs. Since I was replacing the valve cover gasket my mechanic advised to change them at the same time to save money on labour. He told me that they were still working but it was good I changed them to improve performance. I had to change 12 of them at a cost at about $12 each Canadian. Overall job cost around $160 to change 12 spark plugs including tax.

 

I change the plugs on my 2003 E500 every 50k - 60k miles.......helps to ensure smooth operation on my 186,000 mileage vehicle. For the first time I had the plugs (and wires) changed at a local independent MB Repair Shop. The $400 cost was about half the costs at my MB Dealer. I also performed a DIY project to replace all the 8 ignition coils with Bosh units.........easy project just takes times to carefully remove the screws hold the units on so you don't drop and lose one into the engine compartment.

 

Due to misreading the records on purchased car, I was running on factory plugs in 2003 E320 till 170k miles.
The old plugs had electrodes pretty burned out, but I observe mpg very carefully and new plugs did absolutely nothing to performance.

 

I’ve heard the 5-year limit is in there because in some climates the plugs can seize to the aluminum head if you leave it too long. 90% of us are fine leaving it until you hit the 91k service and do it then. Did mine at 103k and had no dicernble wear.

 

right ps2cho.- another myth.
The 170 k miles plugs I was removing were 13 years old and the car spend most of those years in corrosion-prone NY. No problem with removal.

 

 

Just did mine the other day. E350 at ten years old and 95k miles. It was overdue on age but not overdue on mileage. Entire job took 30 minutes and was a no brainer. My earlier 320 motor took 12 spark plugs and a 17mm thin wall socket, but this newer engine required only six plugs and a 16mm (5/8") socket. I highly recommend using a u-joint plug socket for the job; picked mine up at the local parts store for about ten bucks.

The ten year old OE plugs looked okay and weren't too difficult to remove. I replaced with Denso iridium plugs from AutoHausAZ (or maybe it was Pelican Parts). Mfr specifically advised against anti seize and against re-gapping the plugs, so I put 'em in bare just as they were. Car does seem to run smoother and have more power.