Hello All, I am new here, and would like some advise. I have a '04 Buick LeSabre that I bought new and now has about 48,000 miles on it. I have been doing most of the service on it myself, since the car was about 3 years old and the factory service plan expired. Since that time, I have been draining the overflow bottle for the Dexcool coolant and exchanging it for fresh coolant at every oil change. (Every 4 months or so) The first gallon I bought was dexcool and since then I have been using Peak AllMakes. Do you all think I should get a complete system flush ? If so why ? THANKS