Downdraft

Hi, when should the auto transmission fluid be changed? And what about spark plugs? Thanks for any suggestions

rmorin49

I think it's around 6 years not sure of the mileage. I changed mine at 8 years and 30k miles.

maw1124

5yr / 50k for spark plugs and I tend to do my transmission fluid at the same time. In reality for me that's longer than 5 years.

maw

RonNSoCal

I am coming on my next yearly servicing as my SL400 is almost 8 years old. I still have the original spark plugs. With just under 40k miles, I am tempted to continue with them for another year. The engine runs smooth as silk and gas mileage is good so I struggle to convince myself that I need to pony up for new plugs considering the labor cost.

hornethandler

Here's a link to many (including the SL) MY 2017 MB models.
The frequency may have changed over time, but it should get you in the ballpark.

https://www.mercedes-benz.ca/content..._Ed_B__ENG.pdf

TomZVB

With the exception of oil change intervals, follow the maintenance schedule

Oil change intervals should be halved for longevity.

JettaRed

iTrader: (1)

ATF-134FE fluid needs to be changed every 6 years or 60,000 miles on a 2015 or 2016 SL-Class.

JettaRed

iTrader: (1)

The SL400 with the M276 3.0L Bi-turbo is super damned easy to change the plugs on. (Not so much for the M276 3.5L NA engine where it is a royal pain!) The plugs are probably not so critical, BUT if you are driving only 5,000 miles per year, then maybe you need to change them anyway. The maintenance manual does say 46,500 miles or four years. I got my plugs from FCP Euro and returned them because they would not index properly. They were Bosch and identified as Mercedes OEM. I finally got a set of NGKs (NGK96427 SILZKFR8G7S), which are also designated OEM, from Rock Auto that indexed nearly perfectly and all were within 45° of the fuel injector. (If you don't know about indexing, see attached.)

I don't know what you were quoted for labor, but it certainly should NOT be the same as for the NA engine.

rmorin49

I'm in a similar situation. 35k miles but almost 9 years old. No issues so I plan to leave plugs alone until 50k miles.

rmorin49

I'm not familiar with indexing and unclear about how to ensure plug is properly oriented.
Are these correct plugs?
https://www.fcpeuro.com/products/mercedes-spark-plug-kit-ngk-0041597203

JettaRed

iTrader: (1)

Not exactly. We want them to be marked SILZKFR8G7S.

That was the problem I had also with the ones from FCP. I had tried both NGK and Bosch from FCP. The SILZKFR8D7S are older stock.



Read the attachment to post #8 about indexing.

JettaRed

iTrader: (1)

Here are the ones from RockAuto. Both the plugs from FCP and the ones from Rock Auto use the same part number, NGK 96427. But the ones from RockAuto are newer stock.

EDIT: Old stock uses stock number 95875 and new stock uses stock number 96427.



I am a big supporter of FCP, however this time time I was disappointed. When I contacted them about the plugs not indexing correctly, they said our engine doesn't use indexed plugs, which contradicts what Mercedes says. Torquing the plugs to 23 Nm is supposed to index the right plug correctly.

rmorin49

So what is the truth and who has the correct plugs? Rock Auto?

How about these?
https://www.fcpeuro.com/products/mercedes-spark-plug-ngk-90654?

JettaRed

iTrader: (1)

Our engines are explicitly NOT listed for these plugs, so I would say NO. They are also a different stock number, NGK 92725. The plugs mentioned above had the same stock number (NGK 96427), but different part numbers on the plugs themselves.

EDIT: Use NGK96427 (SILZKFR8G7S).

JettaRed

iTrader: (1)

This may help. It's from https://ngksparkplugs.com/en/part-finder

ToeKneee

I believe one of the reasons that there is a short time limit on spark plugs is the concern that they may gall and get stuck in the heads. Of course you could take out the ones you currently have and put them back in again to ensure they're not stuck but not sure how much that would compromise the indexing using plugs that already have had their crush washers flattened?

JettaRed

iTrader: (1)

These really don't come with crush washers. They are solid and flat. They may flatten a little, but I don't think 23Nm is sufficient to really change their thickness significantly. After all, plugs are installed in spec if they are within +/-45° of the fuel injector. I don't think there is any harm in what you suggest, but I also think that if you are going through the trouble of removing existing plugs, why not replace them anyway?

JettaRed

iTrader: (1)

Great timing on this video concerning maintenance based on mileage vs. time...

rmorin49

Thanks. Now, where to buy if FCPEuro has older stock that aren't correct or am I wrong?
Found these: https://www.carid.com/ngk/laser-iridium-spark-plug-mpn-96427.html?fulfillment_ab=B&gad_source=1&gclid=Cj0 KCQjwn7mwBhCiARIsAGoxjaKoWehUkHifAthGxTYYHTWu7niGc 3N5hDNYjzHD1998FkNVnees1K0aAnlyEALw_wcB&gclsrc=aw. ds

JettaRed

iTrader: (1)

RockAuto has new stock, or did you miss that? Why go looking elsewhere? But, if you must, RMeuropean.com also lists the newer part. So does Pelican Parts.

The CarID part does not show a part number, only the stock number, so I would NOT buy from there.

EDIT: Actually, since I realized my mistake and now see that the two plugs use different stock numbers, CarID is probably ok since it uses the correct stock number.

rmorin49

Understood. I agree. I need to calibrate my torque wrench. JettaRed, know anyone locally?

JettaRed

iTrader: (1)

I do not. I have a digital torque wrench and should probably look into that. There is a really good YouTube video where the guy marks his socket and extension to show when the electrode opening is facing the fuel injector. I use that as well as the indicator from the wrench.

rmorin49

Seems plausible once I understand the correct location of the injectors. I've never looked.

JettaRed

iTrader: (1)

RockAuto also seems to be the cheapest.

https://www.rockauto.com/?mfr=NGK&partnum=96427

JettaRed

iTrader: (1)

Due north of the spark plugs (i.e., 12 o'clock position).