If your ATF is turning black quickly it's not from heat, it's from dirt. Somehow particulates are getting in your tranny, either through the vents or somewhere else, or there's an accumulation of sludge in the tranny that the fluid is picking up.
I ran Mobil 1 ATF in the Pumpkin with a Quaife, and it used to get hot enough that I frequently ran a pump and tranny cooler. The fluid lasted a LONG time under hot, high-load conditions and never, that I recall, turned black. I'd change it when I had a significant overheating event and it was usually still nice, bright red. I did run a filter on the vent, which probably helped keep the dirt out.
The SHO MTX was designed to use ATF, and Quaifes like it, too. Many, if not most, high-performance gearboxes these days still specify ATF and that's with a lot more torque than a SHO makes, even modded. I think one needs a pretty compelling reason to use something else. If your tranny isn't working with ATF I think that's a sign that something is wrong with it.
Grab your popcorn, I'm not trying to go against you but I want to get to the bottom of this, but my car does not like ATF, the darkening disappeared but at the same time I know ATF has a lot more cleaning agents than MTF, I agree with you that many applications use ATF but for high performance tranny, I can only find Tremec. Show me which torsen bias diff uses ATF, rear or front? I can only think of SRT4 but not DexIII and leads to a whole lot of other issues.
Doing more research convinces me even more not to use even the Honda stuff or ATF, not an MTXIV but..
Article No.
00-1-9
01/10/00
TRANSAXLE - MTX-75 - NEW TRANSAXLE FLUID - SERVICE TIP
FORD:
1995-2000 CONTOUR
MERCURY:
1995-2000 COUGAR, MYSTIQUE
ISSUE
Several internal changes have been implemented on the MTX-75 transaxle to improve shift efforts. These changes have resulted in the need for a new synthetic transmission fluid for ALL service operations.
ACTION
Use only the new fluid when performing any service on Cougars and Contour/Mystiques built after January 1, 2000. Refer to the following text for additional details.
A new synthetic fluid is required when topping off the fluid level or whenever the transmission is being repaired or replaced in service in vehicles built after January 1, 2000. This new fluid (XT-M5-QS (1 L/quart)) can easily be identified by its "honey" color as opposed to the reddish fluid used previously.
The new synthetic fluid (XT-M5-QS (1 L/quart)) is fully compatible with earlier (1995-2000 model year) Transaxles and fluid. It is recommended that this new synthetic fluid (XT-M5-QS (1 L/quart)) be used exclusively in all model year MTX-75 transaxles when filling a fully drained unit, or when topping off a low fluid level.
PART NUMBER PART NAMEXT-M5-QS Transaxle Fluid (1 L/Quart)
Data Sheet
http://www.fcsdchemicalsandlubrican... Full Synthetic Manual Transmission Fluid.pdf
Even the mustang guys using XT-11-QDC dual clutch trans fluid switched to XT-M5-QS to cure getrag cold shifting problems. However, Tremec stills recommends ATF.
Here is the list of things Terry Haines recommends for that transmission:
"DO NOT USE ATF OR EP type oils in ANY MTX-75*
*Friction mod is not needed....unless 'you' have an issue with the ****...Stay away from it if you can*
*MY Choice of lubes in decending order:-
1. Motorcraft 'Full Synthetic Manual Transmission Fluid # XT-M5-QS ('honey')
2. Royal Purple 'Syncromax'
3. AMSOIL Synthetic 5W-40 European Motor Oil
4. (General) A Full Synthetic 5W-40 Diesel Engine oil...which includes:-
Mobil Delvac 1, 5w40 (full synthetic, a reformulated version of Mobil 1 which is intended for diesel engines)
Chevron Delo 400, 5w40 (full synthetic version)
Shell Rotella T (full synthetic version, not to be confused with Rotella SB synthetic blend or regular Rotella T non-synthetic)"
As for gear oil
Terry Haines says "and no,a gear oil is NOT good in the MTX75...Why are so many fools hooked on 'Gear Oils' over here...GL spec oil usually go in rear ends as in RWD due to hypoid bevel cut gears NOT in FWD MTXs...I'll say it one more time ,even my own MTX75 in my Jaguar X type,AWD uses Ford Honey not gear oil in the trans....The pic is the RP catalog showing Syncromax matches the ford honey part # and the Ford spec.I have NEVER seen any spec sheet that calls for a GL rated gear oil in an MTX75 OK...If some dork puts it in I want to see the spec sheet that say it's OK......doesn't exist!!! "
Although is slightly off here because the spec sheet says GL-4.