the sulpher actualy isn't a lubricant, it is a soft metal, but not lubrication. the problem was that the removal of sulpher also depleted the lubricative properties during the process so in europ they mandated they had to be added back in to a spicific standard. where here the standard is much lower for lubracisity (if I spelt that right)
do you know haw much cetain what you add is suposed to raise it from the base? I wish we were just mandated to hit 51 cetain as a minimum. the diesels we have would burn a little cleaner and get better milage. even highway tractors would benifit.
To a "exact definition" I agree, sulfur isn't a "direct lubricant" in the same function as oil based lubricant. That said, teflon isn't a lubricant, but enhances the "slickness" of the base metal. Sulfur works similarly to prevent "metal to metal wear" in the C4 pump.
If you remember "way back when" Pennzoil was a "sulfur based motor oil" and Quaker State was a "paraffin based motor oil"... If you ever pulled the valve covers from two similar vehicles, one with Pennzoil and one with Quaker State, you would immediately notice the significant difference in sludge buildup in the Quaker State engine.
Sulfur does cause a "protective coating" in diesel engines, but as the fuel oil burns, that expended sulfur is "bad for the atmosphere" so it was mandated to be removed to a lower level. That eliminated the "sulfur coating that reduced metal to metal wear". Europe recognized this and mandated replacement "lubricity properties for their diesel fuel" The US (and I presume Canada) failed to do that.
So, we're faced with increased C4 pump failures due to lack of lubrication properties in a pump that was designed to use the diesel fuel lubrication properties to protect the pump from metal to metal wear...
Posted previously was a comparison to European C4 failure rates and US failure rates. 1% in Europe vs 7% in North America. If that data is accurate, then that's a SIGNIFICANT issue with C4 pump failure based on diesel fuel formulation (assuming all other factors are similar on both continents)...
As for cetane rating. Murphy Oil (where I buy my diesel) ranges from 40-45 cetane based more on climate than on refining. Winter diesel has more anti-gel properties which as I understand it, decreases the cetane rating but allows the diesel to remain liquid so the engine will, at least, start in sub zero temperatures. The diesel additive I use is "claimed to increase cetane up to 6 points". That's a "claim" on the bottle, but how much "up to 6 points" reflects an increase the way I dilute it with diesel is probably significantly different than the way someone in Florida (with less winter formulation properties) would be. I don't know of any way to actually "know for certain" what the cetane rating for any given fuel station bulk tank would be, much less whether Murphy or Marathon or Exxon (which all are supplied by the same distributor in this area) are any different in cetane rating or whether they all "fill from the same distributor bulk tank"....
Anyway, you're correct in saying that sulfur is not a lubricant. But without it in adequate amounts in diesel fuel, the lubricity goes down as the sulfur content goes down... If you don't add some other "cleaner for the environment" lubricant to the low sulfur distillate, then C4 pump wear increases as we've seen in comparing Europe failure rates to North American failure rates.
