2009 brings about the final reduction in the sulphur content in diesel to 10ppm to meet EU targets. Sulphur is pretty nasty stuff that the Catalytic converter is partly employed to catch. What does sulphur do? It lubricates the engine during combustion. On heavy diesel engines they have also noticed problems with oil seals around the FIP area suddenly leaking, particularly prominent on Cummins engines. The sulphur gets into the seals and expands them, thus providing a tight seal, with the reduction in sulphur, the seals relax and may well leak. Engine oil should be at the API CJ4 standard to prevent early engine failures. Caterpillar ECF-3 standard is the designed test standard for engines using fuel of 0.0015% ie 15ppm, and satisfying the API CJ4 criteria. I left the REME many years ago when the OMD70 oil was standard, I believe it is now a fully synthetic oil. I wonder how modern Military equipment will cope when the new diesel standards are fully implemented?