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Transmission Flush

My 2001 Ford Expedition has 200K miles and I have always had the transmission flushed per Ford’s schedule but as far as I can tell, the filter has never been changed? I asked the mechanic and he pours some cleaner and additives when he does the flushes and doesn’t recommend a filter change…this bugs me! Is there a way to change the filter and do a torque converter flush? I was thinking of dropping the pan, changing the filter and then doing a complete flush in 20K? What do you recommend?

Forget the flush completely. If you follow Ford’s schedule, you need to drop the pan and clean/replace the filter, then just refill. While this does not replace all the ATF, and contrary to popular belief neither does flushing, it does provide enough new additives and fresh fluid to keep the transmission working for the life of the car.

“And contrary to popular belief neither does a flush” This is another urban myth.

A transmission fluid exchange machine replaces ALL the transmission fluid. This is the reason these transsmision fluid exchange machines where created. Because it was realized that a pan drop and drain wasn’t enough to properly maintain a transmission. Watch this video.

Transmission fuid is just straight 10 weight oil with the proper additive package. So not only does the oil in the transmission fluid become oxidized, but the additive package gets used up. So unless all the transmission fluid is exchanged, a pan drop and only adding 1/3 of the total capacity of the transmission fluid only results with the new fluid being contaminated by the 2/3’s of the old transmission fluid.


@Tester, I’m not arguing about whether the fluid exchange machine replaces ALL the fluid.

But don’t you think it’s wise to also replace the filter at the proper intervals?

If the transmission HAS a servicable filter then yes.

Did you know some transmissions have filters, but in order to access them the transmission has to be disassembled?


@Tester, yeah I had heard about that, but I haven’t run into one of those yet.

Thankfully, the poster’s Expedition has a serviceable filter. We have these same trucks in our fleet, so I’ve done a few transmission fluid and filter services. They even have a drain plug!

Tester, we once again disagree on this subject. First, that video is just a bunch of Bravo Sierra. Second, the fluid is sucked up from the sump by the transmissions internal pump, a portion goes to the cooler where this machine intercepts it and replaces it with fresh fluid. The fresh fluid is pumped into the sump, TO MIX WITH THE OLD FLUID. The machine just constantly dilutes the old fluid with new, it never completely replaces it.

Also I would like to know what transmission retains 70% of its fluid at a simple dump and replace. The worse one that I know of is Honda which retains about 60%.

And a flush every 24k miles, seriously?

That 70% of old fluid is retained in the torque converter, the valve body, and the transmission cooler in the radiator and the cooling lines.

The exchange of the fluid is complete when the color of the fluid coming out of the transmission is the same color as the new fluid being introduced into the transmission.


I have never had any of my vehicle transmissions “flushed” and have never had a bad transmission. I use the “drop the pan” method and change the filter if there is one.

Flushing, if done right on the right equipment by a qualified technician should not hurt a transmission. The problem is that most transmission shops do not have the right equipment or the qualified technicians to do the job right.

My brother rebuilds automatic transmission for a living and he absolutely loves shops that flush transmissions. That’s why I have avoided transmission flushes for the past 40 years or so.

Teater- I usually agree with and learn from your posts, but that video was paid for by Snap-On which makes the machines, and pays Rusty Wallace tp make these COMMERCIALS.

It doesn’t explain how it manages to suck the fluid out of the mostly closed torus of the torque converter and doesn’t address the issue of the filter.

I know of no manufacturer that endorses this service and I would guess the dealers that do, do so because they invested in these machines which generate large profits without all the stripped pan bolts and leaking gaskets that their ham-fisted technicians caused.

I am guessing you have one of these in your shop and it has colored your view.

The OP states, “My 2001 Ford Expedition has 200K miles and have always had the transmission flushed”.

Gee? I wonder what caused the tranny to last 200K?


Tester Quote: " Gee? I wonder what caused the tranny to last 200K?" Unquote.

Not informative Mr. Tester. You can do better.

Different take, my trailblazer holds 12 quarts, Drop the pan and change filter does 4 qts. of fluid. I was told because of the reverse flow of a flush a filter change is not needed. Me trans fluid and filter change, 30k ago, Rather than spend $150 for a flush, as fluid was tan not red so did a hose attached to the trans line to radiator into marked a bucket and pumped out 12 quarts while pouring in a new 12 quarts, Figured the filter was still ok. It is a pretty red now, 150k and rolling.

Properly done, the pan should be dropped and cleaned before doing a flush. Some flush machines will exchange 100% of the fluid with no dilution as those connect into the pump inlet as opposed to the cooler line method.

FOMOCO apparently condones the flush only/no pan drop method used by dealers. When I pushed FOMOCO on the issue a few years ago they flat refused to say one way or the other.

It’s not difficult to see why a flush only is the preferred method. It’s financially lucrative when comparing 10-15 minutes on a trans flush @ 250 bucks a pop against the time expended on a usually messy pan drop and cleaning along with the filter change. More vehicles can be rolled out the door…

I would never have a transmission flush done on one of my personal vehicles.

NOBODY is going to convince me that leaving the filter in place forever is perfectly acceptable.

Flush all you want, but replace the filter too.

I perform fluid and filter services on my own cars, at 30K intervals.
No problems as of yet.
The filters look absolutely disgusting when they get replaced. I don’t see why I should leave that thing in place.

No one would recommend leaving an oil filter in place forever. Transmission filters shouldn’t be, either.

I suspect that in most vehicles replacing one-third to one-half of the fluid and the filter every 30,000 miles will keep the fluid in reasonably good condition. This does not apply if your vehicle experiences severe conditions causing the transmission to get very hot, like towing. If you do need to replace all of the fluid, or very nearly all of it, the filter should be changed, also.

@f848, some shops tell the customers that flushes are 100% effective and that it’s fine to leave the transmission filter in place forever.

Obviously, I don’t buy into that.

I too share the concerns expressed with the exchange machines.

One concern, not yet mentioned, is that most places using these machines tend to use “one-size-fits-all” fluids. They don’t have to, but it fits well in their high volume business model.
Too many transmissions don’t do well with these fluids.

Never, EVER flush a transmission without first dropping the pan, cleaning it real good and changing the filter. ANY shop that flushes without dropping the pan and changing the filter is not looking out for its customers. They are only in it for the $$.


yes honda