United Oil, a major operator of convenience stores and gas stations in Southern California, will vastly expand its operations across the Western United States after acquiring Pacific Convenience & Fuels of Pleasanton.

In a deal announced late Monday, the Gardena gas station operator said it would take on 251 gas stations and convenience stores from PC&F, adding on to the 128 gas stations operated by United Oil.

Renamed United Pacific, the company will now have 319 company-operated locations, plus 60 locations run by third-party contractors, in California, Nevada, Oregon, Washington and Colorado.

The acquisition marks a big geographic expansion for United Oil, which until now has only operated in California, with most of its locations in Southern California, a United Pacific spokesman said. The deal also adds more than 1,750 employees to United’s 750-person workforce.

United Pacific’s stores operate under the We Got It!, Food Mart, My Goods Market and Circle K Brands, and distribute fuel under 76, Conoco, Shell and United Oil brands.

In a transaction related to the PC&F acquisition, Getty Realty Corp. last week purchased 77 stores from PC&F for $214 million, then leased the properties back to United. A United Pacific spokesman declined to disclose full terms of the deal announced Monday.

United Oil is owned by New York’s Fortress Investment Group, which bought the company last summer for an undisclosed price. United Oil reported 2013 revenue of $3.1 billion, enough to put the company at No. 7 on the Business Journal’s 2014 list of the largest local private companies.