I see people at Halfords buying oil. They just start reading the back of the bottle and then go along the row.
I don't think they even notice the SAE ratings, I imagine this is what they are thinking as they pick up the 0/20 "Ah performance oil that is good! But hey look at the price, this 30/40 sludge maker is cheaper, but I think I go with a brand I trust so Magnatec 20/40 it is."
Then you get oils rated as 0/30 formulated for Ford turbo engines and another 0/30 formulated for VAG turbo engines? Is there really this much difference that an oil of equal SAE needs a rating for a certain brand of engine?