What's the 2002 Chevy Avalanche gas tank size?

The size of the gas tank in the 2002 Chevy Avalanche depends on which engine is in it. The 5.3 L V8 engine has a 31-gallon tank and the 8.1 L V8 can hold 37.5 gallons. Use regular unleaded gasoline with an octane rating of 87 or higher. Using a lower grade could Cause a loud knocking and potentially damage the engine. You shouldnt use gas with methanol in it, it can corrode the plastic, rubber and metal components in the fuel system. The fuel cap is behind the hinged door on the drivers side. Rotate the cap counterclockwise to remove it and hang it on the little tab on the inside of the fuel door while fueling up the vehicle.