I will start with the great positives of this range. Terrific functionality, the double oven concept is a dream come true, especially when cooking for the holidays. The convection option works perfectly, roasts and broils flawlessly. It adds an extra plus to the joy of cooking, and I don't regret buying it. But, the first time I turned on the gas, testing it with some water with a small pot of the simmer burner, there was immediate discoloration on the gray covering of the burner, the black shiny covering of the burner and the grate. I attempted to clean it per the manual instructions but it didn't help. What do you suggest?