It's not an application. It's a question. People have certain oils they tend to favor and these tend to be the current favorites. I'm simply asking why that particular oil appeals to them. You can add PUP into that question too but it appears to have lost ground as of late primarily because of ease of purchase I'm guessing.
All things being relatively equal I usually end up buying Mobil 1 products due to the fact that they almost always have a rebate or special promotion going on that makes it worth my while to purchase their oil.
Over the past year Valvoline has offered fewer promotions but I have purchased an abundance of their products due to limited time low pricing at retailers like Walmart. Recently I purchased 5 quart jugs of Valvoline Synthetic Maxlife for $10.88, earlier this year I purchased the same oil for $3.25 per quart and ordered several.
Castrol rarely has any meaningful promotions or retailer pricing that undercuts the competition, so for the most part I am not interested.