Also, any additives containing sulfur will poison the catalytic converter down the road, which is why such aren't in street car motor oil anymore.
Zinc dialkyldithiophosphate or a closely related compound is found in every (?) motor oil. The "thio" is sulfur that is essential for the zinc phosphate compound to adhere into the crystal structure of the metal. The sulfur that is burned contributes to acid rain and other pollution. It is the phosphate that is poison to the catalytic converter. I think the current limit is 800 parts per million of phosphorus in motor oil.
My post was mostly in reference to molybdenum disulfide, no phosphorus there. Sulfur is also bad for the cat. The advanced emission controls now on diesel cars would soon fail without the switch to ULSD. The sulfur levels in US gasoline are being lowered in order to allow cars to meet Tier 3 certification(diesel ones already do). With ultra low sulfur fuels in place, we will likely see a reduction of it in the motor oil as the oil is becoming a bigger contributor to sulfur in the exhaust.
Of course the ICE gets lubed ... every time it goes to the dealer service center where they change the perfectly unused oil for too many quarts of soon to be unused oil. Bob Wilson
