Of the oil filter gasket being left after removing old filter, Honda Auto had a bulletin on it, if double gasketed owing to oil leaking on exhaust system car could catch fire, has happened a number of times. Of the pre oil filter fill, my Clark forklift has two filters they both have their openings pointing down, does that mean that if the engine is turned off all the oil will drain out of filter? How would one pre-oil them? Granted the Clark engine is not a Cummins, as per Cummins instructions regarding pre oiling oil filter, re Post 42, one should use those instructions for that particular engine, but wouldn't good enginering practice dictate that oil would be drawn from the sump, pumped through the engine, the returning oil forced through filter to rid the oil of accumilated contaminants and return to sump? I have not seen a diagram of the oil system for the Cummins, many motorcycles had a diagram of the direction of the flow of oil as general practice. Not sure of all Harleys but they are dry sumps with the engine oil contained in a tank under the seat. My 68 Sportster had the oil filter in the oil tank under the filler cap, not sure of my 1989 Sportster. I wonder why Cummins have not responded to this contentious subject, it almost has been Flogged to Death. CIA. MI5 who does have the answer? "Does She, Doesn't She?"