I extract the fluid from my reservoir and re-fill with type F ATF every time I change the oil. I also changed the filter when I baselined the car after picking it up.

Overkill, but it only costs about 75 cents to do it. Yes, my fluid always looks and smells like new

edit: I guess what I am trying to say is: change the fluid and filter if you don't know when it was done last.

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2009 VW TDI Jetta Sportwagon 172k miles (rear-ended harder than Elton John on 8/4/13. Total loss)

1991 Volvo 240 142k miles (T-boned by a stop sign runner. Total loss)