Mac181

Before I bought my used 05 F150 STX, 4.2L last month, I took it to a mechanic to have it checked out. Overall, it got a very good report card. He did tell me the transmission fluid looked a bit “dirty” and recommended I have it changed, even though he didn’t notice any obvious issues with the transmission. After the purchase, a friend told me not to touch it. That recommendation was also made by own mechanic (different guy from the pre-purchase mechanic).
The truck had 92K miles when I got it. It had obviously been used for some towing, as there was some wear and a few tears in the rubber step pad on the back bumper (now being replaced). It appears to be pretty well maintained and is otherwise in great condition.
What y’all think? Should I change out the transmission fluid? I notice no slippage or performance issues with the transmission.

ToughFX4

I had the tranny flushed in my 04 f250 at 88,000 and my dads 05 f350 diesel at 110,000 and they never performed the same.(They shifted funny)My friend works at a ford dealership and He recommended only changing the fluid once at 30,000 or leave it alone all together. We also had a 99 f250 with 205,000 and never changed the tranny fluid and it still running strong. My opinion if the tranny seems good leave it alone.

'08f150stx

Change the fluid by dropping the pan and changing the filter too.
DO NOT flush the transmission if it never has before (or you don't know if it has or hasn't)
I know dropping the pan only changes some of the fluid, but a new filter and you can check out what is in the pan is worth it to me.
Lots of threads on tranny fluid changes/flushes

rockymtnrider

I had mine replaced a few months back because I bought it used and I like knowing when the last time fluids have been changed. I took it to the dealer and they refused to "flush" it because it just breaks things so they just did a simple drain and replace. Nothing was broken or slipping before and the fluid wasn't dirty or burnt and everything is still fine. This topic sometimes brings lots of controversy with guys saying to flush it often and others saying they will never flush it.

Mac181

Thanks so much y'all. Man, sounds like a perplexing decision. I'll check out some of those other treads y'all mentioned, to see what I can learn there.
I really appreciate the input.

SAWMAN556

What problems does flushing it cause?

Mod (Ret.)

Some say that if the transmission has never been flushed and it has high mileage (over 70K), a flush can dislodge crud and block passages in the automatic transmissions valve body. If it's bee flushed at regular intervals (every 30K to 50K) then continuous flushing is fine. The problem is that transmission fluid have additives required by the transmission that wear out, just like engine oil. So, if you leave it in, it's worn out fluid. Flush it, and some say you risk dislodging crud.

At the very least, drop the pan and add 4 clean quarts of fluid.

Longarms

Dirty Tranny problems? Are you on the right forum?

Gatorbait2

But even if you add four new quarts wouldn't it still release the {crud} since transmission fluid cleans, so what would be the difference between just 4 quarts or changing all of it?just asking wondering wether to flush mine with 70k miles, I talked to mech I know that works at dealership and he said flushing won't hurt but idk everybody says something different.

ToughFX4

4 new quarts are better than none,when i had my f250 flushed at 88,000 it shifted funny.it would sometimes hold in a gear longer than it should,same thing on my dads truck.More so in the cold.