Group, I know the topic of plugs has been brought up before, but I want to clear up why certain plugs are recommended so I won't won't feel like I did an inadequate job or spent too much money on plugs that a cheaper plug could have sufficed.

While having my ML serviced by an experienced foreign indie car shop, the tech brought it to my attention that the plugs were pretty worn and I should have them changed before winter sets in. He stated that I need to get my plugs from him as he's the only one that has them...at $10 something each.

My guess he's speaking of Bosch's #FR8DPP33, $10.86 online.
Why couldn't I go with the lesser Bosch plugs of: #4301 @ $4.99 or #4418 @ $5.18 or #WR8DCX @ $1.44 or FGR8DQP @ $6.19?

The local auto parts store has #4301 listed for my 98 ML320. I've noticed in other posts that owners have used #4418 and the older #FR8DPP332.

I think you can use lesser Bosch, I bought Platinum 2+ from Auto Zone for about $5 each. It works fine so far for about a year. However, I am thinking to change them again with the factory spec plugs, not because 2+ giving me any trouble, just for peace of mind I think.

That's the peace of mind i'm talking about. Just wondering what makes the $11 OEM/recommended plug jusat that?

I put 12 Bosch Plat 4's in my 99 ML320 at 60K and it "runs like a deer" , with full power and performance. The (12) plugs cost me slightly under $50 as I remember. Will the recommended $12 plug run better and last longer; who knows? I can't believe the more expensive plug could make my ML run any better, but have to wait quite a while to see how long the $4 ones last.

Ben Carter

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Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)

IMHO the plugs MB put in originally are the better plat tipped plugs so they can advertise the "100,000 mile spark plug". Maybe a marketting gimmick, but then again it's nice to not have to change these PITA spark plugs until you get to 100,000. After that the truck is pretty much "your baby" so if you want to jam some copper cores in there, have at it, but probably don't want to wait another 100,000 to change those. IMHO, put in some plat tipped again and don't worry about them for a few years again.
Gilly

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I changed the plugs in two 99ML's at about 60K and 70K and they were easy enough to do, except I had to use extended wrenches (a pipe on the end) to provide enought torque to break loose a couple of the plugs..... I am sure they become much worse at 100K ..... BC

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Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)

I bought all my stuff at O'Reilly - I used the Bosch +2 plugs. I changed them about 25K miles ago and have had no issue. I took the time out on a Saturday morning and did the whole thing the right way. O'Reilly sells a K-D Tool spark plug wire pulling plier that is basically sheet metal with rubber coating on the jaws. They are about $12 but would be worth 10 times as much due to the ease of use -far superior to the 17mm Hazet wrench trick that is prescribed because you can twist the metal ends while pulling with the pliers, and they are set up at a 45 degree angle so that you can get just about anywhere with them. I removed the air filter box, and I pulled the coils individually and laid them out in order so that I could inspect them and run a resistance test on each wire as I pulled them off (they are marked with the resistance, 2K Ohm I believe). Do it on a cold engine - makes the plugs come out much easier. If you remove the air box and coil packs, a single set-up with a straight extension and ratchet will get all 12 plugs. It was extremely easy to do, took about an hour of time going at a slow pace (checking everything, wiping off the parts, visually inspecting each old plug) and much cheaper at $75 (plugs, pliers, and a fresh bottle of handcleaner) versus $225 at an independent shop.

Arkie,

Thanks for your posting. I believe you posted this before, which I saved to a folder for future reference. You appear to work the way I do slow and methodical.

Thanks again,

Kevin

And you get that from an Internet list?

Best you can get is from the engineers that designed the engine.

Pay me now or pay me later.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

For the plugs that can do Km 100 000
So that would mean that one would not need to reset the gap within the Km 100 000.?
If no need to reset gap I would strongly consider anti - seize paste - is that correct

No, you don't set the gap (or reset) on the plat tipped.
You can use anti-sleaze if you want, I'm not a big fan of it. Others opinions differ.
Gilly

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Click here to see the items I have up for auction at EBay

Click here to see a photo album of my '62 Sprite Project Moneypit (Now Sold)

The big secret to any aluminum-headed engine is to change the spark plugs while the engine is stone cold. I'm with Gilly - I would not use anti-seize either. The original spark plugs were made by Beru, and not readily available aftermarket here in the US (I looked before I bought the Bosch +2's that I put in my 98). I would have gladly bought the Berus if I could have found them - they held up really well for 100K.