Exxon Mobil Corp announced it will bring its Mobil-brand gas stations to Mexico, pumping $300 million in the coming decade as it seeks to gain a foothold in the country's retail fuel market. Exxon expects to open its first service stations in Mexico later this year and will offer motorists its Synergy gasoline and diesel fuels, the U.S.-based oil company said in a statement on Wednesday. The company did not specify how many service stations it wo…