firepolice

I have a 2004 F150 FX4 with 120,000 miles. I want to change the fluid in my transmission but i have heard alot of different things, so i am looking for some advise:

I have heard three different things:
1. You should just drain the oil in the pan
2. You shouldnt ever change the fluid just the filter because it does no good to change some of the oil
3. i heard that if you get it flushed and it hasnt been done in a while you take a chance of it breaking down trash and causing problems with the transmission later

f150cwcw

I dont agree with #2. Your manual should say to change it every 30k miles. If you just drain the oil out of the pan, you dont get all of the fluid out, however, if you are doing this every 30k miles eventually all the fluid will get changed out.

I have heard the same thing you have about the flushes. Not sure i would want to have mine flushed. If you have never had the fluid changed in it and have 120k miles on it, the damage has already been done if there is going to be any at all. If i was in your position, i would drop the pan and drain what ever will come out and then put that amount of new fluid back in.

ZX6ROCKET

One and two are complete bs. Three is true. Autotrans fluid is detergent based and if you have never done a transmission flush for the life of your truck it could pissibly eat away at seals and or gasket material. I have had this happen to me before. I had it flushed and it got 3 times worse. If you haven't flushed at regular intervals just leave it be.