When I first got my van I put in some
Wynns Extreme Diesel cleaner - more because I wanted to 'treat' the van. Can't say I noticed any difference.
I've since been using
Archoil AR6900 since the beginning of December - so not long. Gets fantastic reviews.
I haven't been using it long enough to give you an honest review but will report back.
My van is nudging 100K. It was this forum tales of DPF woes that made me do it