Annually or every 20,000 km.
Protective covers of drive shafts are very important elements, as they protect constant velocity joints (CV joints) from dirt, water and other foreign objects that cause damage. External contamination of protective covers with oil and grease can lead to premature failure of the cover material, so it is recommended to periodically wash the covers with soap and water.
Inspect the boots for tears, cracks, and loose clamps. If signs of cracks or grease leakage are found, the boot should be replaced.