MB only requires the DEF tank to be flushed if the vehicle is a low-mileage example that doesn't use the DEF in the tank over extended periods of time. Can't remember the specifics but I think DEF has a 24 month shelf life, in normal service where you're driving the car 10-20K miles a year its a non-issue.

I've got 100K miles on two OM654 engines with the Bluetec system and, to date, I've had absolutely zero issues with any emission component of the system. There are quite a few ideas presented in the linked article that don't make any sense to me at all.

I do see how low-milegage Bluetec cars that were operated in stop-and-go city traffic exclusively could have issues - its very difficult to do a complete and efficient DPF re-gen if the system has to work with low engine loads in cold climates. Don't think I'd be looking at a Bluetec if I was a city dweller, but I suspect most Bluetec owners aren't low-mileage city type drivers.

I'm not crazy about the DEF and DPF components but at least for me they've worked flawlessly so far. Not sure they'll go 300K miles without any issues but I'm hoping to give it a try.

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98 Dodge-Cummins pickup (137K)
13 GLK250 (157k)
06 E320CDI (341K)
16 C300 (89K)
82 300GD Gelaendewagen (54K)