2003 Cadillac Escalade Owner's Manual - Page 308

Fuel The 8th digit of your vehicle identification number (VIN) shows the code letter or number that identifies your engine. You will find the VIN at the top left of the instrument panel. See Vehicle Identification Number (VIN) on page 5-98. Gasoline Specifications It is recommended that gasoline meet specifications which were developed by the American Automobile Manufaxturers Association and endorsed by the Canadian Vehicle Manufacturers Association for better vehicle performance and engine protection. Gasoline meeting these specifications could provide improved driveability and emission control system performance compared to other gasoline. Gasoline Octane If your vehicle has the 5.3L engine (VIN Code T), use regular unleaded gasoline with a posted octane of 87 or higher. If the octane is less than 87, you may get a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you might damage your engine. A little pinging noise when you accelerate or drive uphill is considered normal. This does not indicate a problem exists or that a higher-octane fuel is necessary. If you are using 87 octane or higher-octane fuel and you hear heavy knocking, your engine needs service. If your vehiclehas the 6.0L HO engine (VIN Code N), use premium unleaded gasoline with a posted octane of 91 or higher for best performance. You may also use, middle grade or regularunleaded gasoline rated at 87 octane or higher, but your vehicle's acceleration may beslightly reduced. If the octane is less than 87, you may get a heavy knockingnoise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you might damage your engine. In Canada, look for the "Auto Makers' Choice" label on the pump. Canada Only 5-5