LMB-Z

Change your blinker fluid while you're at it. The air in your tires is also old...I would let the dealer change it too. I'm sure they will only charge $100 to change the air.

BadAV

No reason to change the plugs at your low mileage, even on a Mercedes. You will notice one of several symptoms if your plugs are going bad. Most common is a drop in gas mileage. Hard starting is another. Rough idle is another. Uneven acceleration is another. Pull a couple of plugs and see what they look like if it makes you feel better.

windyC6

Me thinks we at this forum get a little carried away with the term "professionals" these days. Sometimes maybe the wires will need to be changed, and sometimes (most of the time) they won't. But to say that they should be changed every time one changes their plugs is just.....well..... Too many "professionals" these days want to pat themselves on the back by trying to impress the un-informed with knowledge that just may not be true. ......

jaredtxrx

Page 37: https://www.mbusa.com/vcm/MB/Digital...ce-Booklet.pdf

60,000 mile (or 6 years) change interval for GL550. I would not do spark plugs based on time and change at 60k.