Unless you're paying to have it flushed, it's worth dropping the pan and changing the filter. It's the same basis for changing an oil filter every time you change your engine oil. I've changed my trans filter 3 times, but I'm a little eccentric being as my car only has 66k on it. Also most Auto parts stores sell a trans flush( just a can full of compressed air and cleaner) it's great for pushing all kinds of stuff out of the lines and also out of the stock trans cooler. Good Luck
