Never having owned a Bluetec w/DEF, I don't know if there are any TSBs out on the W212's DEF system or if there is in fact an updated/improved DEF tank. If it was my car I would find out if there was actually an updated part available, otherwise would just replace the heating element. I believe MB requires the DEF tank be flushed out at periodic intervals though. The NOx sensor of course, is what it is.

I will say I've found quotes from independent shops (at least in the Atlanta area) not all that cheaper from one of the dealers and then you have unknowns with aftermarket parts, little recourse when problems arise and often no loaner.

The article on the Stephens Service Center site has some good points I think (fuel additive use, engine oil flush with unknown maintenance history, air filter changes, software updates for the ECM, owners not wanting to properly maintain their vehicle), but I certainly don't agree with all of it. Like "Ignore the oil leaks. Continue to change the oil & air filters, but just drive it until it blows up" What kind of advice is that? Also, I feel some of the potential issues are blown way out of proportion unnecessarily scaring people.

For commercial or severe service a heavier weight HD oil may (or may not) be beneficial. There are 5w40 oils that would still protect the emissions system (FCA now recommends 5w40 Rotella T6 in the EcoDiesels), but I certainly would not advise using a 10W60 or 20W60 motorcycle oil!

I don't plan on driving my E320 CDI forever and will eventually upgrade to a newer diesel (if I don't opt for a smaller model). At some point a CDI is going to need expensive work as well, so I'm not sure going backwards is really a solution.