Power Transfer Unit (PTU)- 75W-140 recommendations

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metroplex

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I did a search on BITOG and couldn't find anything using the search feature, so I thought I'd ask.

Ford uses a Power Transfer Unit (PTU) on its AWD vehicles, like the Taurus SHO and Explorer Sport. The owner's manual specifies 75W-140 synthetic gear oil, with a severe duty change interval of 60,000 miles. Doing a Google search will show a lot of frustrated owners with busted PTU's ranging from 20k miles to 60k miles. Some tear down pics show the fluid completely sludged up.

The fill capacity is about 1 quart, and the PTU consists of some bearings and helical cut gears, kind of like a mini differential.

There's no drain plug, only a fill plug at the side of the PTU. I could probably use a suction pump to suck out the old fluid, and then use another pump to pump in new gear oil. I'm used to doing this for filling up the TR-3650 on the Mustang.

What's the best 75W-140 to use for this application? It's not convenient to change every 15k-20k miles, and I'm thinking there has to be a very robust 75W-140 gear oil package somewhere that can handle the stress of this application.

Background: The Taurus SHO has a 6F55 transaxle that uses 12 qt Mercon LV, and a rear differential that is supposed to use roughly 2 qt 80W-90 conventional gear oil according to the owner's manual. The Performance Package equipped SHO and Police Interceptors added an additional (water-to-oil) engine oil cooler, (air-to-oil) trans fluid cooler, and a (water-to-oil) PTU cooler that is integrated into the PTU itself. The non-PP SHO's don't have any of these.
 
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I have been using Amsoil Severe Gear 75W-140 in my Dakota. In such a severe environment as your car, I would stay with a premium lube such as Amsoil, Redline, Motul, ect.
 
It appears a fluid change of 1/3 the severe duty intervals is needed with a synthetic 75W140 GL-5, if that is what is speced.

Amsoil Severe Gear and Redline differntial oils in 75W140 should suffice.

The 1 quart capacity and fluid shear in this PTU sounds like a potential design issue.
 
I think any name brand 75W-140 will work in this application. I changed my PTU fluid at 50000 miles and it looked nasty, almost borderline sludgy. The fill capacity in mine is slightly over 1 PINT, not quart, and I just sucked out the old stuff with a vacuum extractor and filled with a bottle pump.

I used Amsoil Severe Gear 75W-140 in the PTU and also changed my rear differential with Amsoil 75W-90. The rear diff fluid looked much better than the PTU fluid, and the capacity in the rear diff is just over 1 quart.
 
Originally Posted By: MolaKule
The 1 quart capacity and fluid shear in this PTU sounds like a potential design issue.


1 PINT.

A cooler is available through Ford (option code 52B), but only recommended for extended EVOC/track usage -- not required for normal driving.
 
Originally Posted By: Ramblejam
Originally Posted By: MolaKule
The 1 quart capacity and fluid shear in this PTU sounds like a potential design issue.


1 PINT.

A cooler available through Ford (option code 52B), but only recommended for extended EVOC/track usage -- not required for normal driving.


Thanks for the clarifcation.

I was going by what metroplex originally posted:

Originally Posted By: metroplex
...The fill capacity is about 1 quart, and the PTU consists of some bearings and helical cut gears, kind of like a mini differential.



Geez. That IS a low volume of oil for a power transfer unit.
shocked2.gif
 
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My mistake!!

Owner's manual states 18 oz for the PTU (which is just over 1/2 quart).

2.4 pints for the rear diff, or 1.2 quarts

The PTU cooler is integrated into the PTU itself, and there's no easy way to retrofit it onto a non-Performance Package SHO short of swapping out the PTU and buying the coolant hoses
 
I HIGHLY recommend that you invest the time into installing a drain plug like I did this past weekend. The first time you do a D&F you'll thank me. It's nearly impossible to get a hose to the bottom of the PTU to get any of the fluid out and if you've waited too long it won't even be fluid anymore.

At the end of this long thread you'll see my postings with some pics and a decent parts and tools list. It was far easier than I thought it would be and I did it with the PTU in the vehicle.

http://www.fordedgeforum.com/topic/10914-ptu-leak-failures/page-12

After I do several short runs with generic gear lube, I will probably go with Amsoil SVO or Redline 75W-140 and change it every 30k miles or every 4 oil changes.

PS - When I bought the T-Rex with 118k miles on it, the PTU was dry. You can see the sludge I pulled out through the vent hole, as that's what the factory fill-for-life turned into. Luckily, the sellers freaked when they got the estimate to have a dealer fix it and I bought it for a good deal lower than it's value. I've spent about $50 so far to fix this issue.
 
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Originally Posted By: threeputtpar
I HIGHLY recommend that you invest the time into installing a drain plug like I did this past weekend. The first time you do a D&F you'll thank me. It's nearly impossible to get a hose to the bottom of the PTU to get any of the fluid out and if you've waited too long it won't even be fluid anymore.

At the end of this long thread you'll see my postings with some pics and a decent parts and tools list. It was far easier than I thought it would be and I did it with the PTU in the vehicle.

http://www.fordedgeforum.com/topic/10914-ptu-leak-failures/page-12

After I do several short runs with generic gear lube, I will probably go with Amsoil SVO or Redline 75W-140 and change it every 30k miles or every 4 oil changes.

PS - When I bought the T-Rex with 118k miles on it, the PTU was dry. You can see the sludge I pulled out through the vent hole, as that's what the factory fill-for-life turned into. Luckily, the sellers freaked when they got the estimate to have a dealer fix it and I bought it for a good deal lower than it's value. I've spent about $50 so far to fix this issue.

+1 Absolutely install a drain plug. If a pan or unit doesn't come with one, I'll always install one. Saves you a mess and headache in the long run. With that small amount of fluid, I'd change every 10-12k.
 
I agree that its the small fluid volume that's mostly to blame (well, that and trying to make a front-drive car into an AWD, and especially calling it a 'police car', but I digress).

I'd see about retrofitting the cooler option that someone mentioned, as well as running a premium fluid and changing more often. The cooler helps in two ways, though, it cools the fluid and also provides more total fluid volume so that it gets cycled through the gear teeth less often.
 
And you shouldn't have any worries about drilling and tapping the case, as in the spot I picked it was 1/2" thick.

I know how you guys love pictures, so here's one for now.

The first batch of sludge fished out through the vent hole:
 
Originally Posted By: MolaKule
Amsoil Severe Gear and Redline differntial oils in 75W140 should suffice.


How about Royal Purple Max gear with Synerlec? Just curious about your opinion on it in this type of application. Thanks.
 
I plan on changing the ptu fluid in my car roughly every 20k miles or 2 years. The first change has already been done using the German synthetic Liqui molly fluid. I would also use redline or amsoil. Its so stupid the small capacity these have
 
Some more pictures. This is the start of the 5/16" pilot hole:



Pilot hole just broke through:



Finished product:



I even save a good sample for a possible UOA. I did have to add about 10 ounces of fluid when I first got the vehicle, so it won't be a true FF UOA. Like I said the FF was all turned to sludge.
 
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And another random interesting fact is that any PTU that is in a car destined for the Middle East had/has a factory installed drain plug. This goes back to the first Edge models in the 2007 model year.

Ford, why be so penny wise and pound foolish in the NA market?
 
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They have been several units that have either been under filled from the factory or have burned or puked it out
 
Originally Posted By: threeputtpar
And another random interesting fact is that any PTU that is in a car destined for the Middle East had/has a factory installed drain plug. This goes back to the first Edge models in the 2007 model year.

Ford, why be so penny wise and pound foolish in the NA market?

You get a lifetime fill in NA!
grin.gif
 
You can tell this was a bean counter run operation. The Middle East and Australia are probably considered "severe duty" regions, hence the drain plug.

I did some research and found this thread that has a lot of useful information on the SHO's PTU:

http://www.shoforum.com/index.php?threads/how-does-the-awd-work.119781/

Basically the PTU and driveshaft spins all the time. The rear coupler has electronic clutches that controls whether the power is sent to the rear wheels.

So it is fairly idiotic for Ford to use 18 oz of fluid in a transfer case that spins 100% of the time without any cooling.
 
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