i dunno my buddy is a diesel mechanic and he is a real one he has a certificate from the diesel institute to prove it and he said the same thing and im not argueing with anyone but todays fuel is junk no doubt about it. my buddy said they put tranny fluid in all diesel fuel filters after they change then and told me it wouldnt hurt to put some in my truck. i did and it helped my mileage im sure but i am afraid to do it again because the red tint could be mistaken for offroad fuel and a BIG fine.