Roger3116

160,000 km and I have the startup rattle. It only happens when the car has been sitting for over a day. I went from 5w30 oil to 5w40 and it helped. My question is - has anyone tried STP to help this. My thinking is that the rattle is caused by the oil draining off and the STP would help that. Would it cause a problem with the diesel particulate filter? Any thoughts? Roger

B34chBum

Model year 2010 and I think 2011 are known for timing chain stretch (link to DIY on this forum).
Unless you know it has been replaced, this is likely the problem.
Googling "bluetec timing chain replacement" has 3 videos as well, which you might listen to in order to compare noises/sounds.

If you're mechanically inclined/patient/careful/willing to by a few tools, here is the parts kit.

Good luck!

Roger3116

Timing chain stretch. All it took was the Mercedes dealer and $2200 Cdn.

asvancouver

I tried Pensoil recently 5w-40 and it seemed to really help. I had previously been using Mobil or Castrol. 218,000 on my car.