Well it depends how hard you drive the car. How much pressure you put on the bearing and heat taken into the bearing. If you turn a lot on a certain side during your daily driving that wears it out fasten then the others. There are multiple factors can keep going (headache). After ten years or so I would think I would change them to be safe ,but other then that is there servicable bearings aka easy to access then you can be fine the life of the car. When I check multiple cars to see for bearing issues I just do this. Shake them up and down, listen for progressivley louder noise, and possible tire wear. Easy as that nothing to it.

 

thanks sholexman and others who helped me out with the issue.

 

wow 300 for parts and labor. seems very reasonable. my local shops quoting me 400-500. bs. grave digga!!