For some time I have been meaning to read the actual FDA regulations that govern how Nutrition Facts are created and required to be reported. So, over the weekend, pending a response from MM on the questions I recently posed to them (I sent a followup email on Saturday), I studied the applicable FDA regulations (21CFR101.9). For those who are interested in those regulations, see http://edocket.access.gpo.gov/cfr_2011/aprqtr/21cfr101.9.htm
Armed with the FDA information on Total Fats and Saturated Fats, I then went to the nutritiondata.self.com website at http://nutritiondata.self.com/
and examined the various types of oils listed there to see which ones appear to satisfy the numbers on total fats and sat fats as derived from the MM Nutrition Facts. As was recently reported, soybean oil has been ruled out, even though it does satisfy the numbers on fats in the MM Nutrition Facts. Peanut oil and treenut oils can also be ruled out since, according to the MM Allergens pdf document cited recently by Norma, treenuts/treenut oils are not used in any of the MM pizza-related products except for pine nuts (e.g., to make pesto). Interestingly, canola oil just missed the cut (a bit too low on sat fats), as was also the case with sunflower oil, safflower oil, flaxseed oil, and grapeseed oil. Since MM is presumably complying with the FDA rules, I would rule out these oils for the time being.
As for the oils that do satisfy the MM Nutrition Facts, they include olive oil, corn oil and cottonseed oil (unhydrogenated). Sesame oil and rice bran oil also pass muster but it is unlikely that MM is using specialty oils like these. One of the more interesting oils that did pass muster is wheat germ oil. That oil is rich in Vitamin E. One might be tempted to think that maybe that is what MM used in its doughs in the past, but MM only referred to "wheat germ" as part of its flour blend, not the oil of the wheat germ. Moreover, MM has recently said that it is no longer using wheat germ or Vitamin E enrichment, which would appear to rule out wheat germ oil.
So, where does all this leave us? I think it is safe to use any of the basic oils mentioned above can be used to make the MM clone doughs, including blends of oils. I say this for two reasons. First, the numbers for all of the oils mentioned above are all very similar even though some of them do not make the cut because they are a little shy on saturated fats. Second, the amount of oil used in MM's dough as best I can calculate it is quite small. For example, for a 12-ounce dough ball for a 10" pizza (the size I have been using in my MM dough clone experiments), it is around one teaspoon (or about 2.5%). As between olive oil, corn oil and cottonseed oil, I tend to think that MM is not using olive oil, mainly because of cost (although a pomace olive oil would be a cheaper form). Also, if they are using olive oil, I would think that they would promote that fact because of the beneficial effects of using that oil. Cottonseed oil and corn oil would be much cheaper to use. They are commodity oils with no marketing or promotional or health benefit to be derived by touting them to the consuming public.
Edit (1/24/12): Based on recent information, it appears that soybean oil satisfies both the FDA reporting requirements and the MM Nutrition Facts. For the latest, see Reply 1184 at http://www.pizzamaking.com/forum/index.php/topic,3940.msg169124.html#msg169124