Major oil companies buy gallons. It's as simple as it sounds.
If you're a refiner, you have to get rid of product made, one way or another, because there is not a limitless amount of storage for your product. So the major brands will do deals, either with distributors to buy gallons, or if they have a retail outlet - i.e. Vavoline, Mobil, SOPUS products - they will run a special. A third way is large national account business. If you have a large trucking, mining, etc business - majors will buy that business via national account pricing.
Before this purchase, Motiva had no way to get rid of excess product besides cutting base oil deals / spot deals.
Now Motiva will be able to run their own brand, and do deals as they need to, as they have excess product.