If your vehicle has the 3400 V6 engine (VIN Code E) or the 3800 V6 engine (VIN Code K), 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 vehicle has the 3800 Supercharged V6 engine (VIN Code 1), use only premium unleaded gasoline with a posted octane of 91 or higher. In an emergency, you may be able to use a lower octane -- as low as 87 -- if heavy knocking does not occur. Refill your tank with premium fuel as soon as possible. Otherwise, you might damage your engine. If you are using 91 octane or higher-octane fuel and you hear heavy knocking, your engine needs service.