Quote:
Originally Posted by Jeremy5848
The only difference between ULSD and its predecessor is less sulfur. I wonder if the ULSD is pulling sulfur out of the rubber compounds that form the seals and o-rings?
Jeremy
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This is not true. If you perform speciation of the hydrocarbons, you will see this. Hydrodesulfurization is a non-selective process, and it opens up every carbon-carbon double bond and aromatic rings before it gets to the sulfur. The molecular structure of most sulfur compounds in diesel fuel makes it tough to get to the sulfur.
Thus you have a fairly significant shift in fuel chemistry. The sulfur-aromatic compounds used to "alloy" with some of the metal surfaces to create soft, low wear faces, but now you do not have this as much, thus the wear. The change in chemistry to remove the sulfur also changes the solvency parameters, both solving junk and gunk, as well as sometimes rubber parts as well.