Originally Posted by Smacelroy
So I was doing some general upkeep (oil change/fuel filters ect.) I've always taken it in to have this done but seeing how last time they did the oil for me they didn't actually change the oil so now I'm insuring its done. Anyways, I switched out the motor fuel filter and in doing so it had a red tint inside which I noticed after it getting on the new fuel filter. I then noticed down by the o ring when replacing it there was a build up of red goop. Now knowing there is pretty much only one fluid in a vehicle which is red it kinda threw a flag up. I'm assuming this is not a normal build up/collection?
Some people actually put tranny fluid in the fuel as a lubricant/cleaner of the fuel systems. It is NOT a good idea to do this in newer trucks especially DPF vehicles. I know some old 7.3 and 5.9 guys that swear by it.