How do you know when it's time to change the bar on a chain saw.?

My chainsaw is about 10 years old and I have only changed the chain twice, I have sharpened the chains in between and I am about to change it for the 3rd time--I don't use it that often, but I don't know when the bar needs changed. Does it ever need to be changed?How do you know when it%26039;s time to change the bar on a chain saw.?
If the chain still fits in the grove with little side ward movement and the tip roller is still good , then the bar is fine..always use a good quality chain lube, never use detergent motor oil. Keep the chain sharp and out of the dirt and you should keep cutting for some time... Safety first...How do you know when it%26039;s time to change the bar on a chain saw.?
The ridges on the bar will get real uneven and thin.The chain will jump off quite a lot.How do you know when it%26039;s time to change the bar on a chain saw.?
when i put on a new chain and it still wouldnt cut straight ...i knew it was time for a new bar...