I change my transmission pan fluid, filter and adjust the bands every 25,000 miles or so. Yesterday I used my hand pump to suck out three quarts or so of trans fluid out the dip stick tube and refilled it with new. I am thinking about doing this every 7,500 miles when I change my engine oil and filter. Everything I've read about keeping a healthy trans says change the fluid often. I use the truck to commute, haul and tow under 7,500 pounds and have 233,000 miles on the original trans. I'd like to delay buying a transmission as lon as possible. You guys think this is a good technique?