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Stupid put 75W-85 in my MT-82

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Stupid me, that is. I grabbed the wrong red bottle and put in about 100 ml of Motorcraft Synthetic 75W-85 before I caught my mistake. This was the first additional fluid after draining the trans so some contamination remains even after draining most of it. I started over with the correct XT-11-QDC and the trans seems happy. My question is: Should I change the fluid again soon in order to further dilute any remaining diff lube, or am I good to go.
 

JDee

Ancient Racer
1,797
2,001
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
That XT11-QDC fluid is Ford's DCT fluid which they are now calling for in the MT82. I put Motul DCT in mine after it was rebuilt and it has been better than anything I've used before. It is one of the few DCT fluids I could find that meets Fords standard. Amsoil also makes a DCT fluid that might be worth trying as well, though I could not find anything to indicate it meets Ford's standard.
 
98
113
Exp. Type
Time Attack
Exp. Level
Under 3 Years
So cal
Interestingly enough i recently found out when you buy a built Calimer mt82 transmission they suggest using 75w90 so I'm sure you'll be fine.
 
1,119
1,110
Exp. Type
HPDE
Exp. Level
5-10 Years
Lenoir City TN
It depends on where you live and how you use the car. I would have topped it off with the 75w85. The QDC is fine in colder climates for street driving, but is too thin for track use in warm climates.
 

JDee

Ancient Racer
1,797
2,001
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
My trans rebuilder told me that too thick trans oil is what trashes syncros, it prevents them from engaging quickly, that causes accelerated wear and also adds more heat. Those old school transmission fluids are too thick. Heat is a problem with any road course car and you have to deal with it. Hence a trans cooler/pump is pretty much mandatory for any road course Mustang.

The MT82 is a problem child, Ford has been all over the map on recommended fluid for it, the last I saw they recommended their DCT fluid. As I said, I am using DCT fluid and it is shifting better than it ever has, though again that could be partly because of the carbon syncros and a cooling circuit that is keeping temps down.
 
1,119
1,110
Exp. Type
HPDE
Exp. Level
5-10 Years
Lenoir City TN
My trans rebuilder told me that too thick trans oil is what trashes syncros, it prevents them from engaging quickly, that causes accelerated wear and also adds more heat. Those old school transmission fluids are too thick. Heat is a problem with any road course car and you have to deal with it. Hence a trans cooler/pump is pretty much mandatory for any road course Mustang.

The MT82 is a problem child, Ford has been all over the map on recommended fluid for it, the last I saw they recommended their DCT fluid. As I said, I am using DCT fluid and it is shifting better than it ever has, though again that could be partly because of the carbon syncros and a cooling circuit that is keeping temps down.
Ford is recommending their DCT fluid currently. My car was built before they changed the recommendations and it has never had DCT fluid in it. I switched from the stock fill to Redline MTL 75w80 at 30,000 miles and it was still going strong at 94,000 when the clutch started acting up. I am going to have it rebuilt by Ben Calimer while it is out and he is recommending Amsoil 75w90. It looks like different transmission builders have different opinions.
 

JDee

Ancient Racer
1,797
2,001
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
Road miles are nothing compared to track miles though. It's kind of like 20 minutes of flat out on track would be the equivalent of a year of street driving in terms of wear. The heat generated during track use is completely off the scale of what road use heat would be.
DCT fluids are more recent formulations as I understand it than old style gear oils. My car is a '16 and had gear oil in it. I had not used DCT before, I was using conventional trans gear oils from Ford, Redline and BG that are thicker with the idea that thicker must be better. For syncros, it isn't. The damage starts with syncros, then gear teeth get chipped from syncros not working, metal gets shed into the fluid (why is there no filter in a trans??), bearings get damaged and on it goes.
There was a lot of damage in my gearbox using those old school fluids, they clearly did not do what they were supposed to do especially with the syncros, 3rd was the worst but they were all badly worn. 3rd gear was trashed as well, chipped teeth.
This new combination of carbon syncros, DCT fluid and a cooler is the best this trans has ever shifted. But you pretty much should go with what your trans builder is recommending if you want him to stand behind his work.
Regardless of what fluid is used, for a serious road course car a trans cooler is a must. I don't know of any commercially available trans cooler kits, which makes it a difficult task for the average guy to source out all the parts needed. I got everything I needed from Summit, with the exception of one fitting.
A lot of people feel the real fix is a Tremec, and there's good reason to believe that, but their gear ratios suck and they too eventually break down and need rebuilds.
Proving once again there is no free lunch!
 
1,119
1,110
Exp. Type
HPDE
Exp. Level
5-10 Years
Lenoir City TN
Road miles are nothing compared to track miles though. It's kind of like 20 minutes of flat out on track would be the equivalent of a year of street driving in terms of wear. The heat generated during track use is completely off the scale of what road use heat would be.
DCT fluids are more recent formulations as I understand it than old style gear oils. My car is a '16 and had gear oil in it. I had not used DCT before, I was using conventional trans gear oils from Ford, Redline and BG that are thicker with the idea that thicker must be better. For syncros, it isn't. The damage starts with syncros, then gear teeth get chipped from syncros not working, metal gets shed into the fluid (why is there no filter in a trans??), bearings get damaged and on it goes.
There was a lot of damage in my gearbox using those old school fluids, they clearly did not do what they were supposed to do especially with the syncros, 3rd was the worst but they were all badly worn. 3rd gear was trashed as well, chipped teeth.
This new combination of carbon syncros, DCT fluid and a cooler is the best this trans has ever shifted. But you pretty much should go with what your trans builder is recommending if you want him to stand behind his work.
Regardless of what fluid is used, for a serious road course car a trans cooler is a must. I don't know of any commercially available trans cooler kits, which makes it a difficult task for the average guy to source out all the parts needed. I got everything I needed from Summit, with the exception of one fitting.
A lot of people feel the real fix is a Tremec, and there's good reason to believe that, but their gear ratios suck and they too eventually break down and need rebuilds.
Proving once again there is no free lunch!
I understand the heat generated on track. The car has 40+ track days on it as well. Most of those days have been on tracks in the south in 85+ degree temps. It started out as my daily driver and evolved into a mostly HPDE car at this point. I don't know anyone in the south running DCT fluid for track use. Ben Calimer used to recommend 2 quarts Amsoil DCT with 3/4 quart of Amsoil 75w90. He is now recommending straight Amsoil 75w90 due to failures on the track. Your builder is the first I have heard recommending the DCT for track use. I hope he is right and you have found the holy grail for the MT-82. Let us know how it works long term.

I don't think the Tremec is the answer either. It is heavy, expensive and the gear ratios are wrong for these cars. Also a friend has a Tremec in his Camaro and it got so hot at Barber (upper 90's that day) last summer it wouldn't shift right, while my MT-82 with Redline MTL was shifting fine.
 

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