Welcome to the site!
You seem to have the cart before the horse; two UOAs and no understanding of how to read them and what they are good for (and not good for). And on top of that, now you have a BP filter.
Please start by reading many of the good articles linked from the home page, about UOAs.
OTR vehicles are a great place to utilize both UOAs and BP filter, but ONLY if you truly UNDERSTAND how to use them; knowing the pros/cons is paramount to making good OFCI decisions.
When did you install the BP filter? Are either of these UOAs pre or post installation?