yup, when my milkshake just started, I drained the tranny pan (my fluid was still pretty red - only my radiator seemed infected at that point), then I filled radiator full of water (capped tranny lines) and tranny full of tranny fluid, put the input line to the cooler into a drain bucket/pan and added fresh tranny fluid via funnel while it ran for a couple minutes (bucket filled fast and I didn't want too much or too little running through the system). Have plenty of fluid handy! I bought 5 - 8 gallons I think... Once it was coming out nice and red, hooked up to a separate tranny cooler and I then drained pan, pulled filter, replaced gasket and filter and ran through same process all over again, JUST TO MAKE SURE.... Only needed a few gallons on reflush after new filter and pan sealed up.... I felt pretty good there was no other liquid but tranny fluid in there! I guess I put in a new radiator too after I flushed out the cooling system first