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Received motul 75w140 for the differential. I was running some cheap Valvoline for 30k miles and hate how much of it spews out of the rear axle. It would overheat after about 15 minutes of very hard driving.

I am currently waiting on my motul DCTF fluid to arrive as my calimer cocktail has begun to make the MT82 a bit nibbly at high RPM.

90D9641C-7A17-4CCA-9672-D0BD0B7EC6F1.jpeg
 
50
39
Exp. Type
HPDE
Exp. Level
Under 3 Years
Houston, TX
On my V6, I had the same issue for my first 3 HPDE events. In May 2021, I decided to install a Ford Racing finned aluminum diff cover, plugged the axle hole for the vent tube and installed the vent tube on the pre-tapped hole at the top of the diff cover and (5 events later) I have not had an issue with oil spewing out. I am not monitoring my diff temps so an oil cooler is likely necessary, as TMSBOSS is suggesting, to elongate the life of my diff components; but if oil spewing out is your only concern, a diff cover solved my issue.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
6,399
5,275
Exp. Type
W2W Racing
Exp. Level
20+ Years
Blair, Nebraska
V8 or V6 , it really doesn't matter, if you track your car changing the rear diff fluid every 30,000 miles is the main problem. 40 years of racing Autocross, Time Trials, Road Racing, etc. the one thing I heard over and over from Ford , Dodge, and Mazda Engineers was to change the rear end fluid often if you tracked the car. Retiring from the Automobile Business after 30+ years, and selling primarily performance vehicles ( Vipers, Challengers, GT 350s, GT500s, etc.) at Woodhouse Chrysler, Dodge , Jeep, Ram and Woodhouse Ford, we commonly told those road racing their cars or doing Time Trials that it was good to change the fluid after a couple of long weekends. Even racing a Spec Miata years back the Engineers suggested changing the rear end fluid after a 2-3 race weekends. The Boss S specifically gives a change schedule ( from Ford Performance ) based on hours on track and it usually is right about 2 weekends of track time.

Do what is recommended above, but consider changing the fluid on a more rigid schedule. Keep in mind it is not all caused from torque, but also the strain on the rear axle one now gets from the fact that the tires now are gumballs and the lateral loads are way more than one would get with the stock rubber donuts.

PS - for quite a few years Woodhouse Dodge operated Woodhouse Motorsports and they were the premier Dealer for performance upgrades on Vipers. The advice on fluid change came from Engineers with SRT. The Mustang Roundup at Hastings ( race mph.com ) has had Engineers come and race with fellow track rats for over 10 years , so changing fluids more often for track addicts is not new to many this site.
 
V8 or V6 , it really doesn't matter, if you track your car changing the rear diff fluid every 30,000 miles is the main problem. 40 years of racing Autocross, Time Trials, Road Racing, etc. the one thing I heard over and over from Ford , Dodge, and Mazda Engineers was to change the rear end fluid often if you tracked the car. Retiring from the Automobile Business after 30+ years, and selling primarily performance vehicles ( Vipers, Challengers, GT 350s, GT500s, etc.) at Woodhouse Chrysler, Dodge , Jeep, Ram and Woodhouse Ford, we commonly told those road racing their cars or doing Time Trials that it was good to change the fluid after a couple of long weekends. Even racing a Spec Miata years back the Engineers suggested changing the rear end fluid after a 2-3 race weekends. The Boss S specifically gives a change schedule ( from Ford Performance ) based on hours on track and it usually is right about 2 weekends of track time.

Do what is recommended above, but consider changing the fluid on a more rigid schedule. Keep in mind it is not all caused from torque, but also the strain on the rear axle one now gets from the fact that the tires now are gumballs and the lateral loads are way more than one would get with the stock rubber donuts.

PS - for quite a few years Woodhouse Dodge operated Woodhouse Motorsports and they were the premier Dealer for performance upgrades on Vipers. The advice on fluid change came from Engineers with SRT. The Mustang Roundup at Hastings ( race mph.com ) has had Engineers come and race with fellow track rats for over 10 years , so changing fluids more often for track addicts is not new to many this site.
Thank you for the advice. I’ll definitely adhere to it moving forward. Just a note, these are not 30,000 miles on track. The fluid only has 6 hours of track time on it. The rest is daily driving and the occasional pleasure cruise. The new MOTUL fluid made the rear end silent, which was a welcome surprise!
 
On my V6, I had the same issue for my first 3 HPDE events. In May 2021, I decided to install a Ford Racing finned aluminum diff cover, plugged the axle hole for the vent tube and installed the vent tube on the pre-tapped hole at the top of the diff cover and (5 events later) I have not had an issue with oil spewing out. I am not monitoring my diff temps so an oil cooler is likely necessary, as TMSBOSS is suggesting, to elongate the life of my diff components; but if oil spewing out is your only concern, a diff cover solved my issue.
Cortex has some of these for sale on their garage sale page. I’ll definitely pick one up for the next fluid change. Does it work with the stock panhard?
 

TMSBOSS

Spending my pension on car parts and track fees.
6,638
3,802
Exp. Type
HPDE
Exp. Level
5-10 Years
Illinois
Shelby had one which worked well. I can’t remember the name for the other brand. Ed’s I think, was another.
what you want is a quality piece which either fits in the trunk requiring a hole cut in the floor of the trunk or a can bolted to the underside of the truck above the axle. Both should drain back with gravity.

This link may help.
 
Last edited:
Shelby had one which worked well. I can’t remember the name for the other brand. Ed’s I think, was another.
what you want is a quality piece which either fits in the trunk requiring a hole cut in the floor of the trunk or a can bolted to the underside of the truck above the axle. Both should drain back with gravity.
Thank you! This helps. I think I found one.
 
720
1,043
Exp. Type
Time Attack
Exp. Level
Under 3 Years
SoCal
All the catch cans I find seem to be for engine oil. Is there a specific one for the diff?
This is the one that I’ve been using. I put a bit more bend in the mounting arms to get it up as high as possible without contacting the body, and had to slightly clearance section that is opened up for the differential trailing arm bolt. Otherwise it works great and keeps everything mounted outside the interior of the car.

https://bobsmachine.com/product/mustang-2005-14-axle-reservoir-kr-style/
 

Grant 302

basic and well known psychic
You don’t need a catch can if you only vent from the top of the diff cover. Depending on your factory setup, that may mean needing to plug the axle tube if you had a vent there. Both my cars are this way and don’t leak. My GT originally had the vent on the tube, and was overfilled a bit from the factory and puked everywhere. Everything also got quieter with aftermarket fluids.
Lubelocker gaskets also make changes pretty hassle-free.
 
50
39
Exp. Type
HPDE
Exp. Level
Under 3 Years
Houston, TX
Cortex has some of these for sale on their garage sale page. I’ll definitely pick one up for the next fluid change. Does it work with the stock panhard?
I am 99% sure it does. It works with my adjustable from Whiteline. I did have to remove the panhard bar when installing the cover since it protrudes about 1" further back because of the fins. Make sure to sweep the small pool of oil at the bottom inside of the differential pumpkin. A good few ounces of old oil will stay there and will contaminate your new expensive diff fluid.
 
50
39
Exp. Type
HPDE
Exp. Level
Under 3 Years
Houston, TX
V8 or V6 , it really doesn't matter, if you track your car changing the rear diff fluid every 30,000 miles is the main problem. 40 years of racing Autocross, Time Trials, Road Racing, etc. the one thing I heard over and over from Ford , Dodge, and Mazda Engineers was to change the rear end fluid often if you tracked the car. Retiring from the Automobile Business after 30+ years, and selling primarily performance vehicles ( Vipers, Challengers, GT 350s, GT500s, etc.) at Woodhouse Chrysler, Dodge , Jeep, Ram and Woodhouse Ford, we commonly told those road racing their cars or doing Time Trials that it was good to change the fluid after a couple of long weekends. Even racing a Spec Miata years back the Engineers suggested changing the rear end fluid after a 2-3 race weekends. The Boss S specifically gives a change schedule ( from Ford Performance ) based on hours on track and it usually is right about 2 weekends of track time.

Do what is recommended above, but consider changing the fluid on a more rigid schedule. Keep in mind it is not all caused from torque, but also the strain on the rear axle one now gets from the fact that the tires now are gumballs and the lateral loads are way more than one would get with the stock rubber donuts.

PS - for quite a few years Woodhouse Dodge operated Woodhouse Motorsports and they were the premier Dealer for performance upgrades on Vipers. The advice on fluid change came from Engineers with SRT. The Mustang Roundup at Hastings ( race mph.com ) has had Engineers come and race with fellow track rats for over 10 years , so changing fluids more often for track addicts is not new to many this site.
Excellent reminder my sir. I will devote 1/2 hour this weekend to do just that. I gotta make it last as long as I can. That is the reason why I installed oil catch cans, a 925 engine cooler and 3L oil accumulator. If I will protect my engine, I shall also protect my diff and trans.
 

Dave_W

Cones - not just for ice cream
526
558
Exp. Type
Autocross
Exp. Level
20+ Years
Connecticut
If you're not certain, give the Ford Perf. tech line a call to see if they know.

For reference, here's the part
 

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