I've seen reasons from people saying to drain ATF when it's hot, others say do it when it's "warmed up", and others say to do it when it's cold (let the car sit overnight and drain in the morning, for example). Varying reasons are when hot, it flows better. Or when it's cold, any 'sediment' should have settled to the bottom of the pan and come out (vs getting 'caught' in different parts of the transmission before it's dropped down ?).
Finally, at least with a D/F, ATF expands when warm/hot so the amount you measure isn't accurate when you replace it with the same amount of COLD ATF (you'll put in (slightly) too much). I realize one option is to let it drain and cool down and then use that measurement amount. If so, to what temperature - ambient (same temperature as the new ATF that's sitting waiting to be used), 100º F, 125º F ?
Finally, at least with a D/F, ATF expands when warm/hot so the amount you measure isn't accurate when you replace it with the same amount of COLD ATF (you'll put in (slightly) too much). I realize one option is to let it drain and cool down and then use that measurement amount. If so, to what temperature - ambient (same temperature as the new ATF that's sitting waiting to be used), 100º F, 125º F ?