Oil is the life blood of an engine. If you needed a blood transfusion, would you be happy if the doctor said 'we have just got a new batch in - its not quite the same spec as your blood but its good stuff and quite a bit cheaper..........
That’s Funny way of putting it. Can you imagine sitting on a slab in a drastically cut back A&E department with the Dr explaining that you’re blood type O but he’s found some cheaper stuff down at the local abattoir and intends to give you a full transfusion with it?