Below is a portion of the article in the link I posted earlier. It seems that GM gets 36 cents per gallon of Dexos1 certified oil sold, and $1,000 per each product licensed. That is what I refered to as a royalty.
[Get Out Your Checkbook
Of course, the “cover charge” to get into the exclusive “dexos 1″ club will be considerably higher than attaining the less exclusive API licensing. These additional costs are not only due to higher licensing fees ($1,000 per licensed oil plus 36 cents per gallon sold), but are also attributable to the higher cost of developing the oil in the first place.]
Exerpt taken from this source:
Dexos 1: What is This New Motor Oil Spec from GM?
Papasonic