drchpeteros

2009 e350 4matic wagon 121K and plugs never changed to my knowledge. Car runs fine but I guess its past time I do this. 2 questions:

1 - What is the mileage or time interval to change plugs in this car?

2 - Does plug brand really matter? Is there something special about Bosch plugs or can I just use Autolite or NGK Iridium plugs available at local auto parts store?

2MERKS

OEM.. Cant go wrong! Just my opinion

chassis

MB torque spec + MB plugs = MB specified electrode orientation within tolerance.

Aftermarket plugs have different tolerances than MB plugs for thread lead and clocking and crush washer torque vs angle of rotation.

Go OEM from the dealer. The cost difference isn’t worth potential spark erosion issues.

F1Fan

I would recommend either the ones from MB (usually has a Star logo on spark plug) or Bosch plugs that are basically the same as the MB plugs minus the start printed on it. Your owner's manual usually has the specific information on which plugs to use. I would stay away from everything else. Spark plugs are a vital component to the smooth operation of the engine. Do not skimp on high quality plugs just to save money.

drchpeteros

That being the case, I agree the cost difference is irrelevant and I will use the MB plugs. Thank you.

tjts1

I have NGK plugs. Bosch plugs are hot garbage.

Odd Piggy

Mercedes Benz uses both Bosch and NGK spark plugs as factory install on at least some engines. What matters are the specification differences described by Chassis. When using aftermarket plugs, they should be indexed to assure proper ground electrode orientation. The necessity of having to buy extra plugs, along with the effort involved, IMO negates the price advantage of buying any spark plugs except those with the Star logo. Prices from reputable online suppliers are better but I have seen no way to specify brand -they all come in MB boxes. At the parts counter, the boxes can be opened to be sure the preferred brand is bought.

drchpeteros

I took everyone's advice and used OEM. They were Mercedes parts but NGK also stamped on the plugs. As far as I know this is the first plugs change for the car and it's at 122K. A bit hard to turn them out but new ones went in pretty easy. No anti seize so torque would be correct. Wrench was set at 18 ft-lbs from recently doing my outboards so I left it at that since manual said 15-22 ft-lbs. New gap is 0.8 but the old plugs all measured 1.2 - 1.4. Not sure if I should feel or hear a difference but I do not. Sounded and felt fine and still does. No appreciable difference in gas mileage either. Glad I did it as it was an easy job but I have to wonder how long they could have gone for and how I would have known they need changing.

Thanks everyone

cetialpha5

Maybe that's why older threads mentioned NGK I used NGK Laser Platinum. Runs fine. I don't think this M272 engine is too picky about plugs, unlike the M276 engine which requires indexed plugs. Standard recommendation is about 100k on plugs but I haven't checked the MB booklet to see what they say. You don't want to wait too long because you don't want them to seize in there after a long period and end up damaging the head when you take them out. You got your money's worth out of them by going 122k, I wouldn't have pushed it.

https://www.rockauto.com/en/moreinfo...pt=7212&jsn=11

makiii

FYI
My wife's 2010 ML350 4Matic had the plugs change this past July - car had 78,000 miles at the time, they replaced the 11-year-old ORGINAL plugs.
After they were replaced, car got 21.4 mpg - 1st time the car has ever gotten over 21 mpg on the highway !
Trip Shenandoah Valley VA. to Chestnut Hill PA approx. 290 miles

chassis

Maintenance booklet for 2kteens era vehicles is spark plugs at 50k miles. It's good to change them at this mileage because the threads in the cylinder can get sticky from products of combustion and the boots get stuck on the porcelain.

drchpeteros

Agreed. The threads were sticky and difficult to turn at first, squeaking the whole way out. They were in there for 12 years so what can I expect. I won't do that again. I'll do it at the next 50K if it makes it to 172K

juanmor40

I once damaged a spark plug thread on a 1966 VW Beetle, learning mechanics on my own (about 16 years old back then), and I regretted it big time. Since then, I am extremely careful with aluminum heads. I will slowly turn them out, when they get stuck, reverse back in, and repeat. Only force it no more than a few degrees. After a few out/in steps, they come out without much problem. Never damage another one again, but I have had my moments (Renault 18, 1982, 1600cc engine).

YasirKhan

It is strange why no one mentioned about to choose the electrode type i.e. copper/ platinum/ iridium/ Ruthenium etc

In my knowledge MB doesnt manufacturers any kind of spare part themselves, MB places an order to the manufacturer like Bosch/ NGK/ Denso/ AC Delco etc (of course the cheapest one) and that manufacturer becomes the OEM, so basically no difference in buying something which is in MB box packing or something in the OEM packing, the performance specs is exactly the same, in fact could be higher while buying from the OEM/ Aftermarket performance brands

Thanks

juanmor40

A spark plug has a design requirement to be compatible with a given engine: temperature, voltage + gap, etc. The material is selected to accomplish those design requirements and matched for durability. That is, perhaps the engine specs can be matched with copper but it will last say 10Kmiles, but other materials will last longer. So they pick above based on the return of investment, i.e. good for warranty and image, not too much and let the customer pay for a replacement.

Here there is a gray area in manufacturing and outsourcing. For a given set of specifications a manufacturer tries to reduce costs, say make as many as possible as "blanks" and label after the fact. What fact? customer requirements, say top tier for MB, 2nd tier our brand, 3rd tier for other markets (any brand). Once made, it is sold unless it cannot be presented in a box for sale. For example, in the computer industry, do you think Intel makes i3, i5, i7, i9, etc differently? Not by any chance, they are all intended to be high-end. Once tested, they are sorted out and allocated based on market demands. You may end up with a labeled i5 which is in fact a crippled-i7 processor just to maintain supply. This is not by design, but a fact of statistics on quality, some will not be perfect but still usable, so "we find a market for it, and we sell it"

Odd Piggy

For all practical purposes, a spark plug of any particular electrode material functions well when new. Fine wire electrode plugs provide a sharper spark pulse with lower voltage and perform better over time in lean fuel/air mixtures. High density electrode materials [platinum, iridium, osmium, etc] experience less erosion over time and extend spark plug life to the 50k-100k miles seen in today’s engines. This give designers the flexibility to put spark plugs in less accessible locations because they don’t have to be changed regularly. It also has a cost benefit for the manufacturer and a convenience benefit for the buyer.

The only spark plugs I have ever seen in a Mercedes Benz are Bosch and NGK.
If you index spark plugs for performance engines, you learn that there is considerable ground electrode placement difference in the manufacturing process. Indexing is important on some engines, on others it is not. Mercedes plugs are not “pre-indexed” but they are selected with a specific ground electrode orientation. This is done by the manufacturers because they package the plugs and ship them to Mercedes.

That’s not to say you can’t do better. There are spark plugs with exotic electrode designs available that may out perform the manufacturer’s originals for the life of the engine. But they’re expensive. You have to know enough to make a judgement call.