General Motors Dexos Certification and street versus track oil specification for Corvette C7 Z06 and C7 Stingray

+General Motors Dexos certification is a great racket and revenue source for GM.  Although federal law prevents GM from requing DEXOS ONLY oil to be used by allowing "OR EQUIVALENT" clause, the reality is that anyone manufacturing automotive oils will be inclined to purchase the Dexos license instead of insisting on proving the equivalency part (unless the oil profit margin is really small, of course).

Although initially, Dexos certified oil was the only option offered during the complimentary oil changes, saving GM big money in the process, this is no longer the case for Corvette C7 Stingray Z51 and Z06.  Instead of using cheaper synthetic blend oil, these cars receive the fully synthetic Mobil 1 5W-30 oil, including the filler cap label.  Without going into great detail here why this is being done, here is a very odd problem:

Mobil 1 5W-30 (the grade required for street driving) is a Dexos certified motor oil, no such luck with its track duty counterpart, 15W-50 grade recommendation.  Even though Mobil 1 offers this grade, it is NOT Dexos certified and licensed.  More interestingly, there is not a single other brand of motor oil in this grade that carries the Dexos certification and license.

One cannot help wonder, why would +Tadge Juechter and his team require a grade for the supposed track duty if there is not a single brand that complies with GM's own specification?  Considering the severity of track usage, is there a particular reason why this grade would not be available, with Dexos certification?

http://www.centerforqa.com/gm/dexos1-brands