1995 GMC Sonoma Owner's Manual - Page 220

You should keep a record with all parts receipts and list the mileage and the date of any service work you perform. See "Maintenance Record" in the Index. NOTICE: If you try todo your own service work without knowing enough could be damaged. about it, your vehicle Fuel The 8th digit your vehicle identification number (VIN) shows the code of letter for yourengine. You will find the VIN atthe top left of your instrument panel. (See "Vehicle Identification Number" in the Index.j Use regularunleaded gasoline rated at 87 octane or higher. With the 4.3L (Code W) engine, uge premium unleaded gasoline rated at 91 octane or higher for high power performance, when towing a trailer or with a high payload requirement. But when operating with a light load as a normal condition, you may use middle grade or regular unleaded gasolines. The gasolineyou use should meet specifications ASTM D48 14 in the United States 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. In the United States and Canada, it's easy to be sure you get the right kind of gasoline (unleaded). You'll see UNLEADED right the pump. And on only unleaded nozzles will fit into your vehicle's filler neck. Be surethe posted octane isat least 91 for premium, 89 formiddle grade and 87 forregular. If the octane is lessthan 87, you may get a heavy 6-2