Founded in 1948 as one of southern California's largest independent fuel and convenience chains, United Oil operates a high-volume station at 3252 University Ave in North Park's 92104 ZIP code. Drivers combining fuel stops with vehicle upkeep often continue to Oil Changers on the same El Cajon Blvd corridor for rapid-drain oil service. The in-store convenience market carries packaged beverages, snacks, automotive fluids, and tobacco products alongside multi-grade gasoline and diesel fuel islands. Customers preparing vehicles for road trips frequently pair a fill-up here with exterior detailing at Challenger Car Wash across the neighborhood. The station's multi-island layout handles simultaneous fleet fueling for commercial delivery vans and rideshare vehicles staging between North Park and the I-805 interchange.