Originally Posted by DnA Diesel
Montr, the problem is that some dealers interpret the def refill only with scheduled service, so if the DEF requires refill outside of a servicing cycle, it's on the customer's on tab. Other dealers will top the car off until the next servicing period. When the DEF is serviced during a scheduled event, the DEF tanks are purged, and filled completely with new fluid, vice simply being topped off.
On my last servicing, I had been doing notably more city driving and did need to top off my DEF prior to the scheduled service.
This shouldn't be the case. I have spoken to the BMW Product Technology Manager about this exact issue who stated "The 335d should ALWAYS make the scheduled service interval" before requiring DEF.
In some cases such as frequent towing, the X5D MIGHT not.
You may want to discuss this further before accepting this situation.