Keeping it going Yourself gives a lot of satifaction and more understanding of the "beast".
When you eventualy need assistance it is helpfull to add as much detail of your model as possible. Eg mine is a 2017 x290 2.3 130. Twin egr no adblu.
Though many will argue , changing the oil regularly will put you right up there . I change mine twice a year , no matter the mileage , high or low . It's not difficult , and done yourself , costs very little . I would also recommend a high quality oil , personally i use Castrol .
My van is well inside the emission range , despite the van being 23 years old .