change the fluids and filters or just fluids???

[crust productions.com]

94 wagon 4EAT with screw on filter located on side of trans.
Just picked up the car and it has 161k miles.
Doesnt seem to have any issues.
Fluid is very light in color and has some bubbles on the stick.
Shouldnt the fluid be a dark color with NO bubbles?
Subaru says that internal filter is a lifetime filter since its just a metal screen.

So....
should I drain the fluid , clean the internal screen and replace the external screw on
or
Just drain and refill?

What do you all think?

[Buffman]

Trans fluid is usually a lighter red color depending on fill.

[crust productions.com]

Thanx.
Just whipped it out in an hr .
Drained and filled the auto trans, front diff and rear diff.
Fastest fluid change Ive done yet
Haynes manual calls for 4 qts ATF when doing just a drain and fill.
When I emptied my bucket of the old fluid , so as to recycle it, I filled 1 1/4 containers of milk. Each milk container is a gallon . SO by my calculations I emptied 5qts from the pan. Leaves me to believe it was overfilled.
Filled the trans back up with 4 qts penzoil ATF Dexron III fluid and front and rear diff with 80/90 GL5.