FL-Joe is right for the most part. Good fresh DEF less than 6 months old (learn and check the date code) and dont let it get too much below 1/2 tank, and you should be ok.
Spartan is responsible for the DEF system and Cummins for the DPF. Your coach should come with a gen 7 DEF head which so far seems to be ok, but do a little research on that. If they start to fail like all six of the earlier models, you might want to consider carrying a spare since they are always behind in availability. There are differing opinions on that for good reasons, but given limited availability, if they do start failing, it might be worth it (around $1000).
Also my experience has taught me that you should change your DEF filter annually - the 300k miles/3 year standard (or whatever Spartan is saying these days) works for big rigs that are contantly driven, but not for coaches that sit for months at a time. Its around $60 and an easy job - cheap insurance. You wont find this bit of PM info on the web - I learned it the hard way and its my own finding. I carry a spare DEF filter, just like spare fuel filters.
For the DPF part of the system (completely separate and before the DEF part), you should run forced regens periodically based on milage. You cant determine the need without monitoring (based on soot level in the filter) but you can run preemptive regens as preventative maint. I doubt Spartan coaches have the switch on the dash for this but they will have some method for initiating regens. Ask Spartan about it - not your dealer or Newmar.
Since its all under warranty, you dont have to worry about the cost of repairs, but the systems can leave you stranded, and parts can be on back order, so thats what you need to get in front of. The dealers dont know and Cummins wont be of much help (if any) but there is a lot of good info on the internet. Spartan has great customer service so develop a relationship with their owner care folks ahead of time so that when you need them you’ll already know where to turn.
You dont need to stress or worry too much about this as Joe said, but for continued enjoyment, the more familiar you are with it, the better. Consider it a new hobby you didn't really need, but you have it anyway. It could help you avoid a tow, and lengthy stay at a shop, which is the goal. Email me if you have any specific questions. I’ve been stranded three times by my emissions and I feel pretty confident now that Ive familiarize myself with how it all works and how to maintain it. I‘ve driven over 30,000 trouble free miles in the last year.
