In 1968, McDonald's opened its 1,000th restaurant, and Fred L. Turner became the company's president and chief administrative officer. Kroc became chairman and remained CEO until 1973. Turner had originally intended to open a McDonald's franchise, but when he had problems with his backers over a location, he went to work as a grillman for Kroc in 1956. As operations vice president, Turner helped new franchisees get their stores up and running. He was constantly looking for new ways to perfect the McDonald's system, experimenting, for example, to determine the maximum number of hamburger patties one could stack in a box without squashing them and pointing out that seconds could be saved if McDonald's used buns that were presliced all the way through and were not stuck together in the package. Such attention to detail was one reason for the company's extraordinary success.