1993 Oldsmobile Achieva Owner's Manual - Page 214

Sewice & Appearance Care Fuel (CONT.) 2 3 High Output Quad 4 Engine .L In the U.S. and Canada, it's easy to be (Code A): The 8th digit of your Vehicle sure you get the right kindof gasoline Identification Number (VIN) shows the (unleaded). You'll see "UNLEADED'' right on the pump. Andonly unleaded code letter for your engine.You will nozzles will fit into your vehicle's filler find the VIN at the top left your of neck. instrument panel. (See the Index under khicle Identification Number.) Be sure the posted octane for premium Use premium unleaded gasoline rated at is at least 91 (at least 89 for middle 91 octane or higher. You may use middle grade and 87 for regular).If the octane grade or regular unleaded gasolines, but is less than87, you may get a heavy your vehicle may not accelerate as well. knocking noise whenyou drive. If it's bad enough, it can damage your engine. The gasoline you use should meet specifications ASTM D4814 in the U.S. and CGSB 3.5-92 in Canada. These fuels should have the proper additives, so you should not have to add anything to the fuel. If you're using fuel rated at91 octane or higher and you still hearheavy knocking, your engine needs service. But don't worryif you hear a little pinging noise when you're accelerating or driving up a hill. That's normal and you don't have to buy a higher octane fuel to get ridof pinging. It's the heavy, constant knock that means you have a problem. 212