I have 2001 Nissan Altima. 62000 miles and I though it is a good time
to do some check ups here and there. Transmission fluid replacement is
one of them. While I do not experience any problems with transmission
(transmission fluid is a little dark red, does not smell burnt nor it
has any particles on the dipstick) just preventive care. I have a few
options ...flush or drain.

1. Flush. Well I asked here and there and I am a little confused. Many
people do not recommend doing it at all. Nissan Altima 2001 does not
have filter but screen. A guy told that flushing means reverting the
flow of the fluid to the opposite diretion.so all the debris gathered
on the screen will flow back getting stuck in some places causing real
harm to transmission. True I did not find any particles on the
stick ..it does not mean though that they are not somewhere there (in
torquet?). Generally I heard flushing might cause more harm then
good..because (now is funny) I will get rid of the fluid that has some
'good little debris of clutch around it' that supposedly help to
function clutch better. New fluid will accelerate the process of wear
and tear of my transmission (?!). Why all the shops recommend doing
that ? Well it is because of that machine that keeps the process easy
and clean and is a good return for shops to sell the service. They do
not care that you might not be able to shift gears after the flush ...

2. Drain. Old school method .. the process is simple .. uncap, let the
old liquid drain and pour new liquid . Problem : about 50% of old
fluid will stay, we mix old transmission fluid with new (heck if I
know whether old fluid was synthetic or not and if the 1 qrt I poured
some 1 year ago was synthetic or no ....) Supposedly it is not a
problem. The good thing is that the parts of clutch will still live in
the environment where the particles are all around and help to
function the clutch (?!) This will extend the life of my transmission
and is the best option for preventive care ...

Please let me know what you guys think about it. Looks like there are
2 schools ... Those who want to do a decent job and those who want to
sell service .. the problem is I am not sure who is who ..my guts are
telling me : just as you maintain your engine with new oil you should
maintain every other part of your vehicle ....so there the answer should
be out there ;-)))