I am not going to names here, but I have had the pleasure of watching a mechanic at a shop here locally get the oil from the supply room to do a oil change. The Customer specified it had to be Castrol 10w30 and nothing else. Me and the mechanic (A Friend) walk into the supply room where six 55 gallon drums are sitting. He grabs a empty Castrol 10w30 jug, walks over to one of the drums, pumps the pump handle and fills the jug up. Walks out and dumps it in the Customers car. The side of all six drums were labeled Havoline 10w20.
Yet another reason I do not take mine anywhere. You just never know. But name brand is not to big of an issue for me as long as it meets the requirements. The name on the jug does not keep my car running, its whats inside. But that is just me, unless it is mayonnaise and then it better be Duke's.