A 2002 Chevy Tahoe's owner's manual is the definitive source for the recommended oil viscosity. While 10W-40 *might* be acceptable in some situations, it's not necessarily the best choice and could even be detrimental depending on the engine and climate. Many 2002 Tahoes recommend a 5W-30. Using the wrong viscosity could lead to reduced fuel economy, increased engine wear, or even engine damage.
Therefore, consult your owner's manual before using 10W-40. The manual will specify the recommended oil viscosity and weight for your specific engine under various operating conditions (temperature, etc.).
