Thanks guys for the advice. I didn't get to do it myself, when my friend was doing the tranny fluid, he also worked on the broken heater, when he was messing with the thermostat he drained some of the fluid somehow and decided to finish draining and filling it, I don't know all he did because I wasn't there, but I do know that he did not do a flush, just a drain and refill.

I'll take this knowledge and put it towards when I need to do it again in the future.