What Is a Normal Shock Absorber Life?by Sue Williams
Although all shocks give a manufacturer's suggested replacement period, there isn't any way to determine the actual lifespan of an individual shock absorber. The normal lifespan is influenced by real world driving conditions.
The majority of car manufacturers suggest replacing shocks every 60,000 to 80,000 miles. Most shock replacements fall into this time frame.
According to the website Basic Car Repair, "shock absorber life depends primarily on the roads over which you drive." They might fail almost immediately, at say 5,000 miles, or might last well into the 60,000 to 80,000 mile range. The average manufacturer suggested replacement time is between 20,000 and 30,000 miles.
An individual shock may be structurally defective and should be checked periodically, whenever you do basic maintenance. Because there is no way to predict the life expectancy of shock absorbers your best bet is to pay attention to the way your car feels when it goes over bumps. If there is a sudden change and you start to feel residual bouncing after hitting a bump, it is probably time to check the shocks.