I had the transmission oil and filter on my 2001 Accent changed at a garage
last year. It just took 3 litre of SP3. My intention is to drive around a
bit and then drain and refill. I understand that the oil will never be 100%
changed but expect an improvement. Someone mentioned that a drain and refill
will accomplish nothing because the new fluid will remain in the pan.

I have 2 questions.

Is a drain and refill of ATF on 2001 Accent possible without removal of the
pan?

Will a drain and refill of ATF do any good? (20,000 km since last oil and
filter change)

3 liters is a little low for the amount of fluid that comes out. There
should be a drain plug in the pan and another in the differential housing.
If you remove each and reinstall after the trans is drained, a refill
should take four to five liters.

While it cannot hurt to drain and fill the trans, 20,000km is a little
soon. The service interval on transmissin originally equipped with SPII
or SPIII fluid is about 165,000 to 170,000 km.