Kinda semi-moot, I guess. I plan on installing the trans cooler before I leave and doing that will spill some and add capacity as well, that will need to be topped up. I'll count that as a partial drain/refill.

Trans fluid isn't pristine but not dark and doesn't stink, either. My feeling is that lubricating qualities are prob'ly OK, but like the idea of fresh plus fresh additives.

I'm debating adding a thermostat control on the cooler to keep temps in a good range in cooler weather....but I'm on a tight budget and can't spend $100's on it. Any suggestions would be welcome.

Also very open to the idea of manual shut off valves to cooler so I can choose when to use it. Ideas for which valves would be useful, too. I want to be very sure that anything I put on there would be temperature and fluid compatible.