i think flushing it after almost 5 years is a good idea. You wont believe what kind of junk builds up in there. I try and do it every couple of years and it runs noticibly cooler after the flush is performed. First warm your car up and than drain the coolant by removing the plug on the passenger side of the radiator. Than fill with tap water and the flush. You only need to get the car nice and hot and run it with the heater on for a few minutes than drain. However, i did this in the summer (no chance of freezing) so i left the water and flush in there for a week and it really cleaned the radiator well. Note: Running just water makes your car run cooler. Antifreeze does not make your car run cooler but actually hotter. It lowers the freezing AND boiling point of water. That is why it is called antfreeze instead of antioverheat. After flushed you will want to run some more water through the radiator to get out the excess stuff with the heater on again. Than fill with 50/50 water antifreeze. I used 60/40 water/antifreeze with a bottle of water wetter and my car runs noticibly cooler.