Transmission Oil Conundrum

[pup]

2001 Ford Excursion 2WD 4R100 212000 miles

I just purchased this truck and want to change the fluid.

While there are some service records that came with the truck, there are none that indicate the type of fluid currently in the transmission.

The question is:

Seeing as Merc.V and DexIII/Merc are incompatible, is a standard pan/TC drain & filter change enough when switching fluids.

Is it really necessary to switch to a MercV fluid? What is best for an older transmission that has had an easy life, but will be doing some towing now?

[wingnuts514]

should have dex in there, when in doubt i would stay with the usual.

[pup]

my understanding is that if a dealership serviced the truck, the fluid could have been switched to Merc V?

[hansel]

If you plan on doing the work yourself here is what some guys do to get all the fluid changed, you drain the pan and put in a new filter (6-7qts.) you remove the tranny return line running it into a drain bucket. You then fill up the 6-7qts. start the engine and pump out another 6-7qts until you have filled and replaced 19qts. This flushes the old fluid out completely

[dmd]

Yep, that is the way to do it.... Just get the "Fluid formally known a Dex" and
do the fluid swap... you can get that fluid most everyplace still... It is just
labeled kinda strange because they cant call it Dex anymore. They just call it
the fluid that used to be called Dex...