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mtx75 fluid

23K views 30 replies 11 participants last post by  teamDFL  
#1 ·
I was doing whole suspension swap with no engine in, so no cv axle bracket in place, I ended up pulling passenger side cv axle far enough to cause leak fluid on ground.

It was reddish colour, so it is Mercon V or something.

More and more I research, :what::screwy::dunno:

I looked owners manual and some recommends to use Redline D4-ATF which is made for ATX and MTX.

Found Redline website and checked. They recommend to use MTL 70W80 GL-4 Gear Oil, not D4-ATF.

Hmm...:screwy:


There is lot of brands and lot of good feedbacks on Amsoil and Royal Purple.
But didn't say product name, do I use ATF or Gear oil?

I am leaning forward to purchase Royal Purple but MAX GEAR 75W-90 or SYNCHROMAX?
If I can get Amsoil locally, do i go with 75W-90 Severe Gear® Synthetic Extreme Pressure Lubricant (SVG)??

:dunno:
 
#2 ·
..STOP!!...First off ATF fluid has be 'obsolete spec' in an MTX75 for many years now..get it out asap. Correct Ford /Motorcraft synth fluid is Pt # XT-M5-QS but Royal Purple 'Syncromax' is also good for this trans..NEVER,EVER any heavyweight rear end type gear oil...Heavy gear oils do not belong in an MTX75..
 
#13 · (Edited)
So I guess the AMSOIL 75-90 I've been running for 3 years now with 40k+ highway miles and countless drag launches and hard shifting without a single synchro issue is bad for me? I guess when we pulled my trans apart to install the diff and gear, the synchros and old conventional diff still looking like new with no wear had nothing to do with the gear oil used?

I just flushed my trans for new fluid a week ago. It was in good condition, no muck or metal shavings, and I filled it back up with the same 75-90 I've been using since 2008 (http://www.amsoil.com/storefront/mtg.aspx). I wouldn't put anything Royal Purple near my car. Absolutely the worst oil and lubricant out there.
 
#3 ·
ah~~good to know.
do you recommend rp synchromax or different brand?

Amsoil Manual Synchromesh Transmission Fluid 5W-30 (MTF) is a good choice?
 
#10 ·
..first off NO ATB type diff should run in ATF type fluid(see Quaife website/catalog etc) due to high end thrust on planet gears. Ford fluid is matched to the MTX75..RP will work fine but the Ford lube lasts longer under race conditions etc...
 
#15 ·
i m with kogboxking.
i asked and all say that 75/90 or 80/90 is meant for rear differential housing and transmission with limited slip differential in it.

i am gonna try ford first from local dealership. if i like it, i will stick with ford.. or switch to royal purple synchromesh or amsoil mtf
 
#16 ·
Lots of top line Honda shops run and recommend 75-90 in any synchronized transaxle that's going to see a lot of abuse with a Torsen diff. I got the same word from Mazda guys as well. Like I said, I've run it for going on 4 years and 50,000 miles now with 75-90 and it shifts smoother, is quieter, and takes more abuse than any MTX75 I've driven and I've driven quite a few. Best lubricant I've put in it. The factory stuff didn't look too good when I took it out so I didn't try it again, Royal Purple synchromesh caused lots of noise and was hard to shift, so I replaced it with the higher weight AMSOIL 75-90 that was recommended to me. Smooth as could be, shifts easy, and gears look still new.

Everyone has their preference. For me, the lighter stuff ran like crap. I feel the statement that you should never run that weight of gear oil comes from lack of testing with it. The results don't lie. It could also be that AMSOIL is just the best damn oil ever made (with maybe an exception to Brad Penn oil that I consider a tie).
 
#17 ·
Idk if you know who kogboxking is but its terry haines who has done at least 2k plus tear downs on our trans. ill trust him over most. i put 80k mile on my last trans only using ford fluids and you should know how i drive my car and the track days. i just replaced it due to what i thought to be syncro going out buy its my junk comp clutch. 55k miles of those 80k were boosted miles. id say ford **** works.
 
#19 ·
THE Terry Haines. He could build a MTX 75 blind folded, by far the best guy when it comes to these transmissions.

I'm not discounting your experience/knowledge, but making it known Terry knows his way up, down, sideways and backwards through these and has seen it all.
 
#22 ·
As an FYI the spec / weight of oil used in a trans is set,first off, by the type of 'cut' on the gears...A stoc MTX75 gear set is helical and has low tooth pressures and does not need a heavy (say 75/90) gear oil used in a RWD 'hypoid' gear cut rear end...The contact tooth pressure and load spread is the main consideration. Some heavy gear oils have high acid content and do not work well with 'yellow' metals within a transmission.,and as you all know,for a syncro hub/blocker rings to operate correctly(as a mini cone clutch),the lube has to be wiped from the face of the cones so they will bite and the syncro action will operate. Oil with very high shear point numbers and heavy film will prevent correct syncro action..Choose your oil with care. Yes ,I am Terry Haines,ex Ford R&D ,Dunton UK & Dearborn USA etc and have built a few MTX75's!!!
Noted. Thanks for giving the insight. I haven't had a synchro go on me yet though I'm sure it may happen eventually. I flush my 75-90 every other oil change (every 6-8k miles). I'm also an AMSOIL dealer and our car club hosts events under AMSOIL sponsorship so getting it at cost and sometimes cheaper is an advantage. I'm not discrediting or bashing your information but giving a personal review of running high weight oil under stressful conditions with no issues. Would the lighter weight synchromesh work better? The AMSOIL maybe but the RP was complete crap. It was harder to shift on the RP than it is on the 75-90 and noisy as hell. I just like how the AMSOIL will get on your fingers and even after washing your hands, your fingers will still be slippery. :) That's some good stuff.
 
#20 ·
As an FYI the spec / weight of oil used in a trans is set,first off, by the type of 'cut' on the gears...A stoc MTX75 gear set is helical and has low tooth pressures and does not need a heavy (say 75/90) gear oil used in a RWD 'hypoid' gear cut rear end...The contact tooth pressure and load spread is the main consideration. Some heavy gear oils have high acid content and do not work well with 'yellow' metals within a transmission.,and as you all know,for a syncro hub/blocker rings to operate correctly(as a mini cone clutch),the lube has to be wiped from the face of the cones so they will bite and the syncro action will operate. Oil with very high shear point numbers and heavy film will prevent correct syncro action..Choose your oil with care. Yes ,I am Terry Haines,ex Ford R&D ,Dunton UK & Dearborn USA etc and have built a few MTX75's!!!
 
#24 ·
As an FYI the spec / weight of oil used in a trans is set,first off, by the type of 'cut' on the gears...A stoc MTX75 gear set is helical and has low tooth pressures and does not need a heavy (say 75/90) gear oil used in a RWD 'hypoid' gear cut rear end...The contact tooth pressure and load spread is the main consideration. Some heavy gear oils have high acid content and do not work well with 'yellow' metals within a transmission.,and as you all know,for a syncro hub/blocker rings to operate correctly(as a mini cone clutch),the lube has to be wiped from the face of the cones so they will bite and the syncro action will operate. Oil with very high shear point numbers and heavy film will prevent correct syncro action..Choose your oil with care. Yes ,I am Terry Haines,ex Ford R&D ,Dunton UK & Dearborn USA etc and have built a few MTX75's!!!
hmm never knew you were a ford R&D guys thats pretty cool, learn something new everyday.
 
#21 ·
lol, hey terry since were on the subject of opinions, how long do you go between changing out the fluid? im running the ford stuff now, but im having a hell of a time getting in and out of reverse and into 1st when rolling (below 5mph) trans has about 90k on it, i did a manual swap so its from a junkyard. but is my problem fluid or does it need a rebuild??
 
#25 ·
On Amsoil fluids...you may want to check with them which of their fluids meet the Ford spec for the MTX75 which is ..WSD-M2C200-C...

On the Kaaz unit...you will have to follow their info for the oil they need for that diff but be aware that high acid /EP oils can have an adverse effect on yellow metals...


On Ford...I was in Ford R&D (powertrain) for 15 years.Last 6 of those I came over from UK and was on site Ford resident at Roush for the build of 400+ prototype/mule & workhorse cars for the CDW27 (Ford Contour/Mystique/Mondeo)...

For more trans info ...in one place...I have a forum at www.fordcontour.org...Pages of info etc on the MTX75...
 
#26 · (Edited)
Amsoil recommends their european 15/40 motor oil per the rep. I used it for 4 years and never liked it. Gear engagement sucked, very notchy, and the tranny was louder. I have switched to FoMoCo stuff which is a vast improvement in shifting and the tranny is quieter.

edit: after ready Kogs post below it could have been 10/40, either way did not like it. In my defense it was in 05, I think :rolleyes:
 
#27 ·
..OK,I see wher we are bogged down here. The viscosity ratings of engine oil are not the same as gear oil and vice versa...below may assist..




For example, many modern gearboxes use a 75W90 gear oil, which is actually of equivalent viscosity to a 10W40 motor oil.



Gear oils are classified by the American Petroleum Institute using GL ratings. For example, most modern gearboxes require a GL-4 oil, and separate differentials (where fitted) require a GL-5 oil. It is important that purchasers check the oil against the vehicle manufacturer's specification to ensure it does not contain any aggressive chemicals that may attack yellow metal gear components, such as phosphor bronze.
API viscosity ratings for gear oils are not directly comparable with those for motor oil, and they are thinner than the figures suggest. For example, many modern gearboxes use a 75W90 gear oil, which is actually of equivalent viscosity to a 10W40 motor oil. Multigrade gear oils are becoming more common; while gear oil does not reach the temperatures of motor oil, it does warm up appreciably as the car is driven, due mostly to shear friction (with a small amount of heat conduction through the bellhousing from the engine block).
Fully synthetic gear oils are also used in many vehicles, and have a greater resistance to shear breakdown than mineral oils.
API classification subdivides all transmission oils into 6 classes:
API GL-1. Oils for light conditions. They consist of base oils without additives. Sometimes they contain small amounts of antioxidizing additives, corrosion inhibitors, depressants and antifoam additives. API GL-1 oils are designed for spiral-bevel, worm gears and manual transmissions without synchronizers in trucks and farming machines.
API GL-2. Oils for moderate conditions. They contain anti-wear additives and are designed for worm gears. Recommended for proper lubrication of tractor and farming machine transmissions.
API GL-3. Oils for moderate conditions. Contain up to 2.7% anti-wear additives. Designed for lubricating bevel and other gears of truck transmissions. Not recommended for hypoid gears.
API GL-4. Oils for various conditions - light to heavy. They contain up to 4.0% effective anti-scuffing additives. Designed for bevel and hypoid gears which have small displacement of axes, the gearboxes of trucks, and axle units. These oils are standard for synchronized gearboxes, especially in Europe, and may also be recommended for non-synchronized gearboxes of US trucks, tractors and buses and for main and other gears of all vehicles. GL-4 oils may also be used in many limited-slip differentials.
API GL-5. Oils for severe conditions. They contain up to 6.5% effective anti-scuffing additives. The general application of oils in this class are for hypoid gears having significant displacement of axes, generally non limited-slip differentials. They are recommended as universal oils to all other units of mechanical transmission (except synchronized gearboxes specifying GL-4). Some GL-5 oils in this class, which have special approval of vehicle manufacturers, can be used in synchronized manual gearboxes. API GL-5 oils can be used in limited slip differentials only if they correspond to the requirements of specification MIL-L-2105D or ZF TE-ML-05. In this case the designation of class will be another, for example API GL-5+ or API GL-5 LS.
API GL-6 is not applied any more as it is considered that class API GL-5 well enough meets the most severe requirements. When API GL-6 was still in use, it denoted oils for very heavy conditions (high speeds of sliding and significant shock loadings). They contained up to 10% high performance anti-scuffing additives. They were designed for hypoid gears with significant displacement of axes. However, in 2011 at least one company offers new polyol ester based API GL-6 oil, mostly for racing applications. The application is limited to certain types of manual transmissions, but improvements in BSFC of about 5% in standard weather and driving conditions and up to 15-20% in cold extremes (arctic weather conditions) can be expected.
 
#31 ·
If your synchros are worn and scratch on downshift, unless you have absolutely the wrong stuff in there, a fluid change isn't going to do much. IMO, going back to the Ford QS (honey) is probably your best bet. If that helps, consider yourself lucky.