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That makes sense. We have not seen these (essentially) zero ppm P oils show up yet.
We were surprised as well to get the test reports. Being classic car enthusiasts, we are concerned enough to have Harris Laboratories in Houston, TX perform the ASTM standard D-4951 test for Phosphorus. They are one of the largest and well respected labs in the US for petroleum testing, with a particular expertise in oil and additives. When we can, we will post the reports themselves.
The Valvoline was the 10w30 Premium Conventional Oil, and the Mobil 1 was the Extended Performance 10w-30 Fully Synthetic Oil, both claiming to exceed the API SM spec.
The API SM spec for the following oils:
SAE 0W-20, SAE 5W-20, SAE 0W-30, SAE 5W-30, and SAE 10W-30:
max P of 0.08% and min P of 0.06%.
for all other formulations:
no maximum limit, but the min is still 0.06%
The Phosphorus spec is classified as a non-critical spec under ASTM D 3244.
If the EP anti-wear package is based on a different technology such as Boron, then it may explain the total absence of Phosphorus in the oil. If an oil passes all test sequences applicable to the rating, then the actual additive package used is not an issue. Indeed, both Mobil 1 and Valvoline (among many others) have begun putting Boron in some of their formulas.
Unfortunately for those of us who own older cars, Boron is as yet unproven as an EP lubricant in the flat tappet cam/lifter interface. Of course for more modern engines, I doubt there will be any problems. It is unlike a large company such as Mobil or Valvoline to open themselves up to liability on a whim. I can state with equal certainty that they do not consider the liability of older cars being damaged large enough to worry about.
If your car was manufactured before 1988, the engine was designed to operate correctly using SF oils, which had relatively large concentrations of ZDDP, and the flat lifter camshafts and lifter feet were usually heavily phosphated at the time of manufacture to ensure correct break-in.
As far as oil company liability, if someone sustains damage to an older engine while using SM oil as many have, I believe that the oil company's lawyers could make a compelling case that the individual was supposed to have looked in the owner's manual to discover what the appropriate oil spec was for that vehicle. Once again, it is up to the individual to gather the information and make their own informed decisions.
Sorry to go on so long, but this issue has become critical for us old car guys.