It was first known as Sigmor, then Sigmor Shamrock, some years later as Diamond Shamrock and finally as Valero. TETCO came in sometime during a spinoff I think. In the beginning they where cheaper than other outlets. The stations were very barebones, with nothing but a small cashier area, restrooms and vending machines for snacks. They were only there to sell gas and oil with not servicing area. I remember it first being a cash only business. When they started taking credit cards, they would take any other companies card, imprint it and write in your address from your driver’s … Continue reading The Sigmor Corporation – San Antonio, Texas