SL/R231: Spark Plug Replacement
Thread Starter
Senior Member
Joined: Oct 2018
Posts: 380
Likes: 100
From: Orlando, FL
2017 550SL - 2018 560S
Spark Plug Replacement
Took my 2017 SL550 in for aux battery replacement. It only has 11,000 miles on it. So I was surprised when the service advisor informed me they had run some tests and determined the main battery should also be replaced and they were recommending replacement of the spark plugs. 11,000 miles and the plugs need to be replaced???? That was nowhere near as shocking as the $900 charge for the spark plug service. The car is running perfectly fine as far as I can tell. Can anyone offer up the price they have paid for plug replacement? When I do take the car out, I am usually on the interstate and driving 75-80 mph for 45 minutes at a time. The service advisor tells me it's a 3-hour job. I'm not going to get the plugs but would love some feedback from the board.
Super Member
Joined: Mar 2021
Posts: 509
Likes: 217
From: Beech Mountain, NC
E63s SL550 GL450
I would not believe that plugs need to be changed at 11,000 miles and call BS on the service advisor. He would have been challenged to show me that in the manual. Seems to me he is looking for a cash cow to ride like a stolen tricycle.
Newbie
Joined: May 2021
Posts: 3
Likes: 0
SL63 S560
I have a 2013 SL63 with just over 60,000 miles and I just replaced the spark plugs myself. Car was running fine with the original plugs and I decided to change them at 60,000 miles as per the factory recommendations. Car was running fine with the old plugs before I put in the new ones.
If you have patience you can do this job yourself when you milage is higher. My service manual says to do plugs at 60K milage. I bought the plugs from FCP euro along with a skinny plug socket. Was a package deal for less than $100.
My dealer also told me to replace the battery as it is 8 years old but it is working great for me and I declined that.
If you have patience you can do this job yourself when you milage is higher. My service manual says to do plugs at 60K milage. I bought the plugs from FCP euro along with a skinny plug socket. Was a package deal for less than $100.
My dealer also told me to replace the battery as it is 8 years old but it is working great for me and I declined that.
MBWorld Fanatic!
Joined: Feb 2021
Posts: 1,419
Likes: 739
From: Nor-Cal
2020 GLC300 -2014 Sl550 - 1997 SL600
Out Of Control!!
Joined: Sep 2018
Posts: 14,696
Likes: 4,587
From: unbegrenzt
2017 GLE350 4MATIC
Took my 2017 SL550 in for aux battery replacement. It only has 11,000 miles on it. So I was surprised when the service advisor informed me they had run some tests and determined the main battery should also be replaced and they were recommending replacement of the spark plugs. 11,000 miles and the plugs need to be replaced???? That was nowhere near as shocking as the $900 charge for the spark plug service. The car is running perfectly fine as far as I can tell. Can anyone offer up the price they have paid for plug replacement? When I do take the car out, I am usually on the interstate and driving 75-80 mph for 45 minutes at a time. The service advisor tells me it's a 3-hour job. I'm not going to get the plugs but would love some feedback from the board.
The dealer is looking to fleece someone. Don’t be that someone.
Newbie
Joined: Aug 2020
Posts: 10
Likes: 4
From: Essex uk
Sl400 (450 USA)
Took my 2017 SL550 in for aux battery replacement. It only has 11,000 miles on it. So I was surprised when the service advisor informed me they had run some tests and determined the main battery should also be replaced and they were recommending replacement of the spark plugs. 11,000 miles and the plugs need to be replaced???? That was nowhere near as shocking as the $900 charge for the spark plug service. The car is running perfectly fine as far as I can tell. Can anyone offer up the price they have paid for plug replacement? When I do take the car out, I am usually on the interstate and driving 75-80 mph for 45 minutes at a time. The service advisor tells me it's a 3-hour job. I'm not going to get the plugs but would love some feedback from the board.
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MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,636
Likes: 522
From: Hagerstown MD
2015 SL400; 2019 X5M40i
Service is about the only area of the car business that generates a lot of profit. Dealers are often telling customers they need more work than the manufacturer recommends in their owners manuals. Once my SL is out of warranty I will likely not return to the dealer.
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Member
Joined: Sep 2020
Posts: 165
Likes: 33
From: Stockport UK
SL 350 R231
In my view it's advisable to remove and replace ( not renew ) the spark plugs every 2/3 years so they don't seize in the heads, especially with a low yearly mileage car. Personally I do about 4k a year so it will take a long time before the plugs reach 50.000 miles. Spark plugs degenerate with how many times they spark, not how old they are. The thing with the crush washers doesn't wash (pardon the pun ) with me because when the plug is refitted and torqued down to 23 Nm the plug will be at the same attitude to the injector as it was before as the crush washer is already flat. A lot of it is scaremongering by MB to deter people from carrying out their own servicing and repairs.
Member
Joined: Sep 2020
Posts: 165
Likes: 33
From: Stockport UK
SL 350 R231
YouTube is the place to go. Some say to remove the inlet manifold or plenum chamber which is the same thing, but you don't need to. Look for a video from Senior Leigh, I think it's the best one.
MBWorld Fanatic!
Joined: Jan 2017
Posts: 1,040
Likes: 234
From: God's County (Yorkshire)
Shanks’s Pony
My car is going for it’s 4 year service and spark plugs are one the schedule. Happily I purchased a 3 year plan (4,5&6) when MB UK was offering a good discount. The independent that does my wife’s MB couldn’t match them.
Super Member
Joined: Jul 2018
Posts: 563
Likes: 171
From: Nothern Georgia, U.S.A.
'17 SL450, '25 Lyriq, '25 Sonata Hybrid, '96 Corvette GS coupe
Plugs are strictly mileage, period. And as to the 60k recommendation...GM recommends a 100k plug interval on the ZR1 Corvette. If GM can build a 700+ hp engine that doesn't need plugs until 100k miles, wth is wrong with MB? And the Chevy's plugs are a good deal cheaper as well...
