ive been involved in plant using red diesel for a long time and there is a lot of old wives tales about it....as said before it is identical apart from the red dye,and it does not stain the tank or engine..ive put it in my van before when ive run a bit short and got checked 2 weeks later and all clear....nearly got caught another time though..run out of diesel on m23 at 3 in morning so gets 5 gallon of red out of back and started filling van up with funnel and police t5 pulls up behind me....thought that was my lot but he asked if everything was ok,so told him yes just run out of diesel ....i filled up and turned it over until it started and he said he would follow me for a few miles to make sure it was ok...he turned off motorway at next junction to my relief.....he must off known as it was a transparent 5 gallon drum shining red in his headlights