Good of you to bring this up!
Seems that it would be smart to pull some VOAs on most "questionable" adds (things that wouldnt normally be used in an IC Automotie application) before using. While inorganics have been used as part of the additive packages of fuels, and so we should likely assume that they are able to burn clean, it is likely also smart to minimize the use of higher additized adds unless we know they are OK to use in emissions-controlled (catalyzed) equipment and/or that they wont foul them beyond regular (no additives) baseline for >150k miles of use.
Surely at the ratios being used, and at the low levels seen, it is nowhere near as bad as, say, a car that uses 1qt of oil per 1000 miles... We could do the math on that given the concentration of adds, fuel used, TCW3 ratio, etc. In fact, to answer your question, take a baseline API SM/SN oil, look at Mo, Zn, P, etc. Figure how much mass of these adds would be burned if you burned a qt of oil every 1000 miles. Then, using your car's MPGs, figure the mass of those metals in the adds if you put it in at whatever recommended ratio, and youll have your answer in terms of the equivalents of quarts of oil burned every 1000 miles. If it comes out to be less, then youre set.
Do we have any VOAs on MMO? I seem to think that we did...
