Does costco give discount off of posted fuel price.

I used to work across the street from a Costco that sold gas and was always amazed at the number of vehicles lined up for 45 minutes + to get gas. Reminded me of the gas lines from the 70s. There was also a Valero on the corner whose prices were always within 5-10 cents of the Costco and they never had a line. You can't fix stupid!