dyed/off highway is now 500ppm sulfur. used to be unlimited. undyed/on-highway is now 15ppm sulfur. used to be 500ppm. ford-6.0L and back are designed for at least 500ppm. any less, and you start to see problems-injectors, pumps, general fuel system pressurization failures. 6.5turbo and back chevy/gmc. non-commonrail cummins and back. basically any HUEI, or mechanical/semi-mechanical injection system will have issues. as long as it doesnt have after treatment or a CP3 pump, you need 500ppm, or a very high quality additive (i use standyne's products in everthing... even the d-max). better mileage, less rattle, less wear. dyed fuel comes with the price of possible citations tho. in VA its like 1000 bucks plus a per gallon fine (like $1000 plus i think it's $20 per gallon of your tank's capacity) if you get dipped...