BIO or non BIO fuel ?

I have a diesel RV on a Sprinter chassis. The owner’s manual says “Refill only with … ultra-low sulfur diesel (ULSD) with a maximum sulfur content of 15 ppm.” “Fill up with ULSD (B5 or less) whenever possible.” Diesel engines may run great on bio, but for my rig there are precaution noted and use of bio may invalidate the warranty.