Sure, I would use the exact oil recommended by the manufacturer too (since one simply can't afford to take any chances with the engine given all the horror stories one reads on the internet) but I can't help feeling that there is some advantage being taken of naive customers as well.

BTW, I wouldn't use oil which is more than 6 months old in my car. I wouldn't be confident about its viscosity over time even if it's fully synthetic. I prefer to buy small quantities regularly rather than larger quantities less frequently.