I don't even bother with oil at the parts store anymore. They started selling the big jugs in 5 LITER sizes instead of 5 QUARTS, so every damn time I'd change my oil, I'd have a little more than 1/4 quart extra that I'd just throw away. I've never owned a car that required more than 5 quarts, and even if I did, I'd buy a 5 quart jug and a 1 quart bottle(s). 5 liters of oil in the USA is useless.
On top of that, half the parts stores don't stock Motorcraft filters. Wal Mart does, so against my better intentions I buy all my oil change stuff at Wally world. They carry 5 QUART jugs of all the good oil brands, too.