Chain rattle on cold start. Actuators go bad. Replaced all four cam actuators, all chains and guide assemblies tensioners and both of drivers side cams. I suspect if i had adressed sooner I would not have had to replace cams. Also replaced some of the roller rockers. Oil changes were performed every 7500 miles with full synthetic. Parts came to around $3k. Cams were dealer only at $1k each.

Ive already replaced the radiator and all rotating items on front of engine including ac compressor.

Stick with rear wheel drive if you dont need 4matic. Less stuff to maintain on RWD.

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Jim