2006 chevy impala ss 115,000 miles runs hot,fluid in reservoir boiling

Are your cooling fans operating?, is your water pump operating? is your thermostat opening? these are the thing you will need to look into that may be causing the car to over heat.

I would also check out the radiator, when did you last flush the system? Could be bad fins.

Whatever happened to the "maintenance free timing chain " auto manufacturers love to advertise? It's marketing bullshit and let me tell you, when your timing chain fails, it will disable your car and you immediately, sometimes causing partial or complete engine failure. Yes, there are some warning signs like excessively noise, but, really, how many people are going to pay attention to this with all of the other sounds they hear in their cars. There's noise from the engine, road, window leaks, etc. If you really think that your timing chain is almost done, it's time to sell the car. And, at 115,000 miles on a domestic car, that's a lot of miles. This is why I think in many ways it's easier to manage a timing belt. There's a set schedule for replacement of the belt and once it's done, your car will be running in top condition. The timing chain can also stretch over time and decrease your performance. Look, it's more expensive generally to replace the timing chain and much more difficult, increased labor even if you do it yourself. SO, if you determine that you have to put almost $2,000 in your car, will you keep it?