Grand Mobil 22628 Golden Springs Dr, Diamond Bar, CA91765 Grand Mobil is a service center located inside the Mobil station across from the Chili's on Grand and Golden Springs…More Drive. Owned by Tim Foster, the shop has been operating for more than 20 years in Diamond Bar. It offers inspections, smog checks, oil, filtering, lube services, and battery changes. The gas station itself offers 12 pumps, diesel and a snack shop. Water and air pumps are provided to customers free of charge.