I just dropped off my 2011 F250 6.7L with a local ford dealer for a transmission fluid flush and coolant flush. The service adviser told me they recommended not flushing the transmission since it has high millage (281k). Does that make sense to anyone here?

 

No one "flushes" transmissions, they simply do a fluid exchange by letting the trans itself pump old fluid out and draw new fluid in when they disconnect the cooler lines and install their BG or whatever flavor machine in line.

That said, you can't do an exchange on a 6R140 without a heated exchange machine due to the fact that the trans has an internal thermostat to control cooler flow and very few dealers even have the heated machine.

If it were me, drop the pan, change the filter and refill with fluid.

 

Has the tranny ever been "flushed"? Some folks feel that flushing a high mileage tranny that's never been flushed will knock internal crud loose resulting in a leaky and/or non-functioning tranny. The customer immediately blames the shop for causing the tranny to stop working.

I agree with drain/refill yourself. Repeat in a week or two.

 

In my opinion, that is like saying that you shouldn't change your engine oil because your engine is dirty.

Change the fluid. You have filters to deal with any trash.

 

 

The basis of this philosophy is that old dirty transmission fluid when not changed eventually becomes severely impregnated with contaminates, mainly metal particles. Transmission fluid operating inside of a transmission is essentially hydraulic fluid. over time the metal particles inside the fluid act as sandpaper to the components it travels through effectively boring out passages in the transmission. New, "more viscous" fluid will not act the same way in a transmission that fall into this category(250k without a change). You could potentially loose pressure and not be able to activate the solenoids and accumulators effectively. Not sure if this applies to you or not but that is where the statement comes from.

 

my opinion...

if damage is already done.... ... its done

but if limited issues... put in fresh.. might help in the long run..

I would change.. then change again in a few months..

if it fails.. it was doomed before you started. and the change did little to help it along

the only transmission filters I have seen "CLOGGED" were ones with destroyed clutches... or pumps.. not small bits of trash..

the do not change fluid.. as your dealer said.. is the same with chrome muffler bearings and 3,000 mile oil changes...
that is SO 1960......... and need to be put to bed.. 6 feet under bed...

 

If the trans has had regular fluid filter changes at the recommended intervals you are ok. If not IMO its a crap shoot.

Each and every time I have changed trans fluid in a high mileage trans with an unknown service history I have regretted it. It ****zt the bed within 1000K.
Now keep in mind this was with analog transmissions(as they should still be) in my youth with muscle cars that took a severe beating which they deserved.
The theory was two-fold:
One, the solids floating around in the fluid acted as a cushion/lubricant for the clutch packs in a trans at the end of its expected service life. Remove the cushion and the almost expired clutches and steels will fail.
Two, the replacement trans fluid was a newer revision of the factory accepted replacement fluid. Which means all the good stuff was removed by big brother to save the spotted owl and the fluid no longer has the proper lubricity spec'ed for the OEM clutch pack. This causes accelerated clutch pack wear to a trans which again is at its service limit.
You make the decision.
The stealership made this decision based on past history. So I don't imagine I'm tossin uric acid into a fan...

Drop the fluid in a clean pan. Drop the pan and look at how much smuckis is in the pan and on the magnet. If its very heavy just put the pan back on and dump the used fluid back in and save your coins for a rebuild. Cuz at ~300K your at that limit IMO...(gasket is reusable if carefully removed)

Note there is zero scientific data to support my theory only 40 years of grease under my fingernails.

 

yeah i dont get it
drop pan
drain fluid
change filter
put new fluid in

 

Not to me.
There is a tiny grain of truth to this.

Many people ignore the transmission until a problem develops. Then they realize that they have never serviced the trans so they do that. And then the trans fails. It failed because it was ignored until something went wrong. New fluid didn't fix the broken part and it failed. If the fluid hadn't been changed it would have failed, too.
They are wrong.
This is totally wrong. Particles in the fluid are the major cause of solenoids sticking.

New fluid can only help a transmission, not hurt it.
I agree.
Bull.
I have at least that much experience, I also owned and operated an auto repair shop for a while. I changed fluid on older transmissions that my techs told me were going to fail from that. They were wrong. I never had a trans fail after a fluid change.

 

Thank you Sir, I value your advice and opinion.
retired auto mechanic.. 50 years..

 

 

this is a urban legend which , like all legends , has some cultural foundations.

old transmissions have very work friction plates and the friction particles in the fluid (which remains due to window screen type of filters) provides some added friction. on these old worn out trannies...once you change the fluid and loose the friction plate particles that is in the fluid...the transmission slips.

 

"This is totally wrong. Particles in the fluid are the major cause of solenoids sticking."

That's exactly what I said.

I don't care about people telling me I'm wrong but don't follow that up by essentially quoting me. It's a philosophy that exist in the automotive world and it's existence doesn't make it true but it does exist. The point of my post was to explain the origins of the statement. It's up to you whether you believe it or not.

 

It's unfortunate when a dealer doesn't even have proper knowledge of the hardware they're working on. All else fails, follow your manual for service reqs. At least those things were somewhat written by legitimate engineers.