I have about 145k on my truck. I pull up to about 6k every now and then, and when I'm not pullin I do admit I get on the truck a lot. Its chipped and all that good stuff. I bought the truck used and dont know if the fluid in the trans has ever been changed. A few months ago I put a tru cool in line with my factory cooler and the old fluid did have a burnt smell to it but it looked clean and red. I'm looking for advice about getting the transmission flushed. I've heard its bad because it shakes up all the metal and stuff in the pan and causes damage. Would I be better off just draining it then refilling it? TIA