If 40 cetane has more lubricity than 45 cetane, should I stick with 40?
Here are the answers as I understand all of this. If I goof, Joe D. can straighten us out. The lubricity differences between high sulfur and low sulfur fuels is related to the lubricating value of sulfur (BTW sulfur compounds are what make 90W gear oil stink). Most highway fuel has another lubricant added to keep the injector pump plungers from sticking. The P7100 injector pump used on 94+ Rams uses internal lubrication from the engine oil pump and additional lubrication is not needed. The Ram/Cummins specifies a minimum Cetane rating of 42. It will run on lower Cetane fuel, but may produce some smoke and have lower fuel mileage. Cetane is (sort of) an indication of the delay between fuel injection and fuel ignition, and the higher cetane of low sulfur fuel is a byproduct of the refining process to remove sulfur. The lower the cetane rating, the longer the ignition delay. For fuel economy and emissions, longer ignition delays produce effects similar to late pump timing. The higher ceta
