Change Driveline Fluids Early!

[ThunderFlash]

I just completed changing the fluid

Carbon, thanks so much for posting all of this. Just did the rear diff fluid and installed an ARB cover at 18K miles on my WT. This thread was extremely helpful. Fluid was not too bad but had the metal schmutz on the magnet. Used the factory gasket and Motorcraft syn oil. It seems very thin. I was mildly surprised how stout the OEM cover was. Expected thinner gage steel. I increased all the bolt lengths by 5mm as you suggested and metal brake line retaining clips. I did not realize there is a little sump area in the bottom axle housing. Maybe the large drain plug in the ARB cover will let me suction that sump out next time with out removing the cover. The brake line seems a little low on the driver's side in the dip for the exhaust clearance, so I need to play with that. Also the Borla Climber exhaust make the access for the installation and top filling on the ARB way easier. I was actually able to carefully pour from the nipple on the Motorcraft bottle.

Kind of a bummer the track bar covers the ARB labeling...chalk one up for the FP marking guys. Maybe when she lifts her skirt up in the off camber stuff, it will show.

Thanks again. Rest assured your efforts are making the world a better place! I'm not sure what pure testosterone smells like, but I bet it has a hint of hypoid gear oil smell to it. I love that smell.

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[PWillette]

Re

The oils were flowing like wine this weekend. At 10K miles (5K interval)...

- Emptied J&L Oil Separator...about half ounce of oily snot.
- Oil & Filter (new Quaker State Full Syn 5-30 / AFE D2 Filter)
- FDU (new Valvoline 75-140) OEM fluid didn't look bad, thin layer of snot on the magnet.
- 7MT (new Redline MT-LV) With all the rattling I figured there would be metal...actually looked good.
- Transfer (new Redline D6 ATF) OEM fluid looked good. No magnet on the drain plug.
- RDU (new Valvoline 75-140) Very concerning...had installed the ARB diff cover and replaced the fluid only 3K miles ago so I was going to let it ride another 5K, glad I didn't. The 3K fluid fluid came out very dark w/ plenty of metal flake and the magnet had big ball of metal flake the size of a marble built up. Looks like I'll be changing again at the next 5K interval.

Rear diff fluid change #3 @ 15k miles.

- First change at 7k miles (75-140) when I installed the ARB cover...very dark metal flaked oil.
- Second change at 10k (75-140)...oil still dark and big ball of snot on the magnet.
- Third change at 15K (75-140)...oil looked great, still clear. Small ball of extremely fine metal on the magnet.

Looks like she's pretty well broke-in now. I'll probably go to 10k interval.

 

[CarbonSteel]

Re


Rear diff fluid change #3 @ 15k miles.

- First change at 7k miles (75-140) when I installed the ARB cover...very dark metal flaked oil.
- Second change at 10k (75-140)...oil still dark and big ball of snot on the magnet.
- Third change at 15K (75-140)...oil looked great, still clear. Small ball of extremely fine metal on the magnet.

Looks like she's pretty well broke-in now. I'll probably go to 10k interval.

You should be able to move to a 20-25K OCI from this point forward. I have about 500 miles to go to hit 25K and I will change mine again and send it out to be tested.

I want to install my temperature sensor probe for my ISS Pro axle temperature gauge into the FP cover, but my doctoral studies have taken most of my free time.

Heat is what "kills" the fluid in an exponential manner, i.e. for every 10°C increase in fluid temperature, fluid life is cut in half. The D44 in my 2019 Wrangler ran hot with 4.10 gearing and 33" tires running unloaded at 75MPH in 95°F weather on the order of 220°F:

I have to assume that given the D44 in our Broncos is nearly the same except for mounting points that it runs about the same temperatures.

 

[PWillette]

You should be able to move to a 20-25K OCI from this point forward. I have about 500 miles to go to hit 25K and I will change mine again and send it out to be tested.

I want to install my temperature sensor probe for my ISS Pro axle temperature gauge into the FP cover, but my doctoral studies have taken most of my free time.

Heat is what "kills" the fluid in an exponential manner, i.e. for every 10°C increase in fluid temperature, fluid life is cut in half. The D44 in my 2019 Wrangler ran hot with 4.10 gearing and 33" tires running unloaded at 75MPH in 95°F weather on the order of 220°F:

I have to assume that given the D44 in our Broncos is nearly the same except for mounting points that it runs about the same temperatures.

If you change your doctoral major to oil studies you'll have all kinds of time!

 

[B22-2023]

You should be able to move to a 20-25K OCI from this point forward. I have about 500 miles to go to hit 25K and I will change mine again and send it out to be tested.

I want to install my temperature sensor probe for my ISS Pro axle temperature gauge into the FP cover, but my doctoral studies have taken most of my free time.

Heat is what "kills" the fluid in an exponential manner, i.e. for every 10°C increase in fluid temperature, fluid life is cut in half. The D44 in my 2019 Wrangler ran hot with 4.10 gearing and 33" tires running unloaded at 75MPH in 95°F weather on the order of 220°F:

I have to assume that given the D44 in our Broncos is nearly the same except for mounting points that it runs about the same temperatures.

While installing the probe, why not plumb in a fin cooler for th e heck of it?

 

[CarbonSteel]

While installing the probe, why not plumb in a fin cooler for th e heck of it?

Not sure how that would work given that an axle does not have a pressurized oiling system (it is splash system).

As much as I love the FP cover as it has nearly every feature except a temp probe port, I wish it was made of steel instead of cast iron. It would be so easy to weld a 1/8" NPT threaded bung into it.

I am going to have to either drill and tap it (there may be enough material) or have a threaded bung brazed into it which means I will need to recoat it. Which is not all bad--I'll probably have it bead blasted and recoated in black.

 

[vwarner1411]

Did the front diff, transfer case, rear diff (added the ford performance cover), and the transmission fluid (added the ppe deep pan - changed the gasket and filter as well) at basically 17k miles.

Used mercon ulv in the trans, mercon lv in the transfer case, and amsoil severe 75w90 in front and rear diff.

We did run into a couple issues, though nothing too major. The transmission pan stud bolts on the passenger side were tough to get a socket on - very little space between the bolt and the pan. We put about 8.75qts of fluid in total. When we filled the pan cold, we put in about 7qts and that filled to level 5 on the dipstick. We then got the transmission up to my normal operating temperature (about 180F) and the dipstick only had maybe 1-2mm of fluid. Added fluid until it was back to level 4 while idling. A note, the exhaust and cat are right by where you reach for the fill port, and doing it hot requires care.

The biggest issue we had was the ford performance diff cover. The driver side stud bolt broke (see picture) when we torqued it to the specified torque values included with the cover (using a recently calibrated torque wrench). We were lucky that we were able to grab the bolt with pliers. We ended up using a new oem gasket and the factory bolts, and torqued to the stage 1 and 2 values specified in the service manual.

I wish we had read this post first as we wouldnt have torqued it down to the ford performance specs.

Rear diff magnet had some metal mayonnaise (see picture). Other magnets had some metal as well. Transmission pan had some metal on the magnet as well, and the filter looked dark, but the fluid looked fine honestly.

 

[timbits588]

Probably over-thinking this one, but following the link to the longer flange bolts used for the Ford Performance cover, the yellow zinc plated ones have been sold out for awhile. Would it be alright to go with the regular zinc plated ones that are in stock?
Did a quick google search and it shows they're both corrosion resistant. I just figured it couldn't hurt to ask, since there seems to be a lot of knowledge and background from the folks in this thread.

 

[CarbonSteel]

Probably over-thinking this one, but following the link to the longer flange bolts used for the Ford Performance cover, the yellow zinc plated ones have been sold out for awhile. Would it be alright to go with the regular zinc plated ones that are in stock?
Did a quick google search and it shows they're both corrosion resistant. I just figured it couldn't hurt to ask, since there seems to be a lot of knowledge and background from the folks in this thread.

They will rust. The threaded bosses are deep enough that you can use the 30MM yellow zinc version which are in stock.

 

[timbits588]

They will rust. The threaded bosses are deep enough that you can use the 30MM yellow zinc version which are in stock.

Thank you! Appreciate your time and dedication to this thread and helping us all.

 

[anomdeplume]

Changed the front differential fluid today and the transfer case fluid. 26000 miles. Went with Mercon LV in the transfer case and Valvoline 75W140 in the front differential. Still deciding on a possible aftermarket rear differential cover but that should be soon. Plus I’m still nervous about removing the brake line clips. Thank you to the members of the forum (especially Carbon Steel and Ducati1098). This is my 1st time changing differential fluid myself. Transfer case fluid looked okay but there was a little gunk around the magnet. Front differential fluid smelled a little burnt and there was a lot of gunk on the magnet. This really surprised me since I’ve only been in 4wd for 50 miles total. Here’s the obligatory nuts and junk pics from the front differential.

 

[anomdeplume]

Changed the rear differential fluid today. 26777 miles. Stayed with factory cover and gasket for this time. Thanks again to all the information in this thread. I have very little to add to the conversation but will comment on a few things. Fluid was dirty but not as bad as my front differential. The rear must’ve been under filled at the factory. I only got out 1.5 quarts. There was a small amount in the sump that I wiped out but not 16 ounces. The underfill alone is reason to check/change the fluid early. I put in just over 2 quarts of Valvoline 75W-140. I was quite nervous about breaking the brake line clips. I put some photos below to show them closed and open. Careful prying and poking with screwdrivers did the trick. The 2 step torque process is a pain with the vehicle on the ground and the trackbar in the way. I managed. Some gunk on the fill plug but gears looked good. This was my first time ever doing the rear fluid myself. Third 4WD I’ve owned over 30 years. Again, thank you to the forum members for their guidance. (The picture of the plug is in the cover. I did loosen it before starting the whole process to make sure I could get it out.)

 

[Karl_in_Chicago]

Changed the rear differential fluid today. 26777 miles. Stayed with factory cover and gasket for this time. Thanks again to all the information in this thread. I have very little to add to the conversation but will comment on a few things. Fluid was dirty but not as bad as my front differential. The rear must’ve been under filled at the factory. I only got out 1.5 quarts. There was a small amount in the sump that I wiped out but not 16 ounces. The underfill alone is reason to check/change the fluid early. I put in just over 2 quarts of Valvoline 75W-140. I was quite nervous about breaking the brake line clips. I put some photos below to show them closed and open. Careful prying and poking with screwdrivers did the trick. The 2 step torque process is a pain with the vehicle on the ground and the trackbar in the way. I managed. Some gunk on the fill plug but gears looked good. This was my first time ever doing the rear fluid myself. Third 4WD I’ve owned over 30 years. Again, thank you to the forum members for their guidance. (The picture of the plug is in the cover. I did loosen it before starting the whole process to make sure I could get it out.)

Outstanding photos for reference! Thanks for sharing.

 

[87-Z28]

Changed the rear differential fluid today. 26777 miles. Stayed with factory cover and gasket for this time. Thanks again to all the information in this thread. I have very little to add to the conversation but will comment on a few things. Fluid was dirty but not as bad as my front differential. The rear must’ve been under filled at the factory. I only got out 1.5 quarts. There was a small amount in the sump that I wiped out but not 16 ounces. The underfill alone is reason to check/change the fluid early. I put in just over 2 quarts of Valvoline 75W-140. I was quite nervous about breaking the brake line clips. I put some photos below to show them closed and open. Careful prying and poking with screwdrivers did the trick. The 2 step torque process is a pain with the vehicle on the ground and the trackbar in the way. I managed. Some gunk on the fill plug but gears looked good. This was my first time ever doing the rear fluid myself. Third 4WD I’ve owned over 30 years. Again, thank you to the forum members for their guidance. (The picture of the plug is in the cover. I did loosen it before starting the whole process to make sure I could get it out.)

I replaced my diff cover and was able to reuse the two brake line clips. I don’t want to discourage anyone from going the route carbonsteel generously provided. If you are careful it is possible to reuse the clips. I am probably just way to lazy and cheap.

 

[CarbonSteel]

I replaced my diff cover and was able to reuse the two brake line clips. I don’t want to discourage anyone from going the route carbonsteel generously provided. If you are careful it is possible to reuse the clips. I am probably just way to lazy and cheap.

Agreed; the caveat is that Ford does not sell the clips separately. You must purchase the entire brake line to obtain them. I defaulted to my solution because it is much more durable.

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