When to change tranny fluid?

[biznaga]

My 2004 ST is approaching 65,000 miles...maybe a few past that...haven't looked lately.



Anyway, I have not had one iota of tranny trouble with it. Should I have the tranny fluid flushed and replaced?



Kinda scared to let the local Ford dealer do it but I can drive 85 miles to dealer I trust. I am afraid it will act up if anything is changed.

 

[Robert Caffyn]

Some will say don't change it until 100k miles, others say flush and fill it at 60k miles. I did mine at 40k miles(f+f and filter) and it runs better than new. Follow the manufacturers recomendation and use Motorcraft fluid(synthetic)I personally feel that 60k is as far as I would go before it was changed. Bob

 

[Fred]

I've heard a few bad stories about tranny flushes going bad. They say it changes all the fluid, which maybe it does, but not the filter? I'm not wild about that idea, plus I don't like letting anyone else work on my stuff. Where does the crud go that the filter caught? I'm no expert by far, but I much prefer dropping the pan and changing the filter. I do know it doesn't change all of the fluid. I've done it every ~30 - 40K on my '02 ST and so far so good. Changing the fluid and filter yourself is easy and you know it's done right.



Here's pictures of my unwiped pan and the filter during the ~70k fluid change.

Good luck with whatever you do.



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[Johnny O]

On an '04 the manual calls for flushing the tranny every 30k. So you've more than doubled the interval. You can get away without it, but Ford automatics won't last much past 100k if you don't. Ask my sister.

 

[Richard L]

What does the fluid look like? Does it smell burnt? I suspect that you have been gentle on the tranny but it should be changed.



In numerous other threads I have discussed the different pro's and con's of the Tranny Flush vs the conventional drop-the-pan fluid change.



People seem to be very concerned about the tranny filter, and about the dirt it traps clogging the system. Tranny filters are not designed to trap an hold dirt and debris like an engine oil filter or they would need to be 5-6 times larger to last 30K miles. Tranny filters do not have to deal with combustion by-products. Tranny filters are Surface filters that prevent larger particle from getting pumped through the transmission. When the engine is shut off, the pump stops and the debris stopped at the surface of the filter drops to the bottom of the pan where it is attracted to the magnet and stays there harmlessly.



Particles that make it through the filter are too small to do any damage and the filter should easly last 100K miles as long as you keep changing/flushing the fluid regularly.



The fluid is the life blood of the transmission and contains special friction modifiers. if the fluid is burnt the friction modifiers are damaged and that will cause the transmission to slip. Slipping will generate more heat and continue to damage the fluid as well as the transmission. When fluid gets burnt it starts to turn into a sticky varnish like substance that clog filters and coat parts in the valvebody that cause sluggish shifting, slipping and wear out bands and clutches.



If that were my vehicle, I would have the fluid flushed ASAP. That will replace about 98% of the fluid and you may just notice an improvement in how the transmission operates..even though you did not have any problems.



I had the fluid flushed in my 2001 Sport Trac at about 32K miles. The transmission was working fine and I was a bit nervous. I was amazed that after the flush the transmission shifted much firmer and even the acceleration off the line was noticabley quicker.



I had my 2003 Sport Trac fluid flushed after 25K miles at the same shop and there was no difference... but the 2001 had more miles, the fluid was darker and smelled a little burnt. The 2003 fluid was not as dark and did not smell burnt at all.



You can choose either method, but I would say that you need to have the fluid changed soon.



...Rich

 

[EddieS'04]

:banghead:

 

[biznaga]

Thanks all. :driving: Just the info I needed.

 

[TrainTrac]

I concur re: flushing ASAP. Especially given the fact that you used your Trac for towing a RV.

 

[Dreman]

Put a drain plug in that pan and drain and re-fill every so often. I do that every other oil change, then change the filter once a year. But I drive a lot and change the oil every month.