Many thanks for the reply. We just replaced both of ours and hopefully they'll last a while. I believe these were the first one replaced on this engine. we have 450K miles on her right now and we are doing Pm's every 10k miles just to be on the safe side.
Thermo shock and expansion is what ultimately makes them fail. To help extend life, always idle the engine for several minutes before shutdown after a long hard pull and always open the hood during a parked regen to let excess heat out.
DD15 is a better made engine. Smooth, quite engine. Much less vibrations. X15 has loud crackling sound. If price are the same, DD15 all day everyday
While I have you here...what you think of the 2016 N13 engines. Seeing plenty on sale with mid 300k miles