1994 Cadillac Eldorado Owner's Manual - Page 254

NOTICE: If you try to do your own service work without knowing enough about it,your vehicle could be damaged. FUEL Use premium unleaded gasoline rated at 91 octane or higher. It should meet specifications ASTM D4814 in the U.S. and CGSB 3.5-92 in Canada. These fuels should have proper additives,so you should not the have to add anythingto the fuel. In the U.S. and Canada,it's easyto be sure you get the right kindof gasoline (unleaded).You'll see "UNLEADED" right on the pump. And only unleaded nozzles will fit your vehicle's filler neck. into Be sure the posted octane is at least91. If the octane is less than you 91, may get aheavy knocking noise when drive. (Inan emergency, you you may be able to use lower octane as low as 87 -- if heavy knocking does -not occur.)If you're using91 or higher octane unleaded gas and still you get heavy knocking, your engine needs service. 242