What kind of fluid for 4 wheel drive 2006 trail blazer?

For a 2006 Chevrolet TrailBlazer with four-wheel drive, you should use GM's Autotrac Transfer Case Fluid, which is specifically designed for the transfer case in these vehicles. If that is not available, you can also use a high-quality automatic Transmission Fluid (ATF) that meets the specifications outlined in the owner's manual. Always refer to your owner's manual for the exact specifications and recommendations to ensure proper performance.