2005 Ranger 3.0 V6, 4x2, automatic trans, 169,000 miles.
Family has had this truck since new. It has never been used for towing and rarely heavy loads.
Lately, it shifts a little hard sometimes going up a slight hill at about 40 MPH.
The trans fluid is just at the bottom of the full range on the dipstick. Fluid looks and smells good.
The trans fluid has never been changed.
Should I get it drained and filled, or just top it off and leave it alone? I don't want to invite trouble. We rarely use it, about 1,000 miles a year.

 

I’d change the internal filter and change the fluid twice. Clean the inside of the pan too.

 

^^Yup. The fluid is 20 years old and just plain 'wore out'.