a person i know from alabama bought a used 5.9 like a 1999 or so model year that the po had been running veggie oil in it... only to find out a month later that it needed an injection pump.
some people run a mix of oil and diesel also.
from other diesel bbs's i have surmised that just using diesel is probably best...
now... all the wvo people will comment..
i would like to hear from people using wvo who have racked up like 500,000 mi on it..and had the same diesel truck or bus with similar mileage to compare maint costs...