Spark plugs after 12k

[markjay]

My last MB was on on a service plan for the entire duration that I owned it. So changing the spark plugs at 4 years and regardless of mileage was a no-brainer.

I also have two Suzuki cars, and paid the dealers to have the spark plugs replaced at the due intervals. Not convinced it was necessarily, but for what it costs, I thought I'd have it done.

Not criticising anyone who does not care about FSH and leaves the spark plugs in the head for longer than the manufacturer recommends. It's your car.

 

[fabes]

Mine are at (only) 3 years, so I'd be within what most have inferred would be "tolerance", if.....

Not sure what the cost is to be fair

 

[W1ghty]

Mine are at (only) 3 years, so I'd be within what most have inferred would be "tolerance", if.....

Not sure what the cost is to be fair

I wouldn’t over think it buddy , another year or two will make absolutely no difference

 

[as400]

So ORIGINAL Merc spark plugs x 8 (for SLK55 R172) = £160 and gawd knows what a main dealer or indie would charge.

Or

8 X BOSCH £75 or less?

Is there anything special about original Merc plugs?

 

[190]

Is there anything special about original Merc plugs?

Someone will give you a more definitive answer for your car but there are MB engines which require the plugs to be indexed which means the alignment of the plug gap and earth electrodes need to point a particular way - usually the open side of the plug gap towards the inlet valves. The MB supplied plugs will ensure that the correct alignment is achieved.

Once the correct alignment is known you may be able to replicate it with standard plugs and washers. I would certainly try this as I've indexed plugs before and have spare washers.