Mercedes-Benz engine rattle M276 M278 Remove/install/check/replace chain tensioner W166 W212 W222 

Crankshaft at 40° TDC, but verify based on your engine model.

@@German-garage thank you

Wear and tear

Wear & tear at 78,000km? How come? Whats d other reason?

@andrewmachine1 lack of oil change,poor maintenance,ignoring oil change interval,I seen those engines reach 200k+ miles with proper maintenance

What the best oil grade shall i use? 0w 40 or 5w 40?

@andrewmachine1 here in florida. I use 0w40 for older engines m112 m113 and 5w40 for newer models,I recommend ordering oil from the local dealership by the vin#