How often do you change rear diff fluid

[tyman]

I changed mine out at 55k on the Silverado and 20k on the CRV.

 

[CarbonSteel]

Interesting data. You presented the concept of “ cumulative iron”, which is not really true because the magnet inside most diffs takes much of that out of solution. That’s what the “mung” is on the magnet. Case in point, do a test on a fluid that was in the diff for 100,000 miles. That’s why many manufacturers call it a lifetime fluid. I change at 50,000 miles, but most vehicles will make it to the wreckers with the original fill. The owners manual for a 2022 Ram 1500 calls for changes at 30,000 miles. I see you are doing changes at 5,000 miles. Wow.

Whether or not iron is trapped by the magnet, the cumulative iron that I show is what was shown to be in the oil by the UOA so it is tangible and valid. Now, to your point, it means there is more iron in the oil than the test shows NOT less and some of the particles trapped by the magnet can be too large for the UOA to detect.

 

[Snagglefoot]

Whether or not iron is trapped by the magnet, the cumulative iron that I show is what was shown to be in the oil by the UOA so it is tangible and valid. Now, to your point, it means there is more iron in the oil than the test shows NOT less and some of the particles trapped by the magnet can be too large for the UOA to detect.

You drained and disposed of the fluid, correct. Then you added fresh fluid, ran it for 5,000 miles, then drained and tested it, correct? If so the cumulative iron is a hypothetical number. The interesting question would be, what would happen if you went 100,000 miles and then drained and tested the fluid. I would bet it wouldn’t be that same as your cumulative iron number, because the magnet would take a lot of the iron out of solution. That’s the only point I’m trying to make.

 

[CarbonSteel]

You drained and disposed of the fluid, correct. Then you added fresh fluid, ran it for 5,000 miles, then drained and tested it, correct? If so the cumulative iron is a hypothetical number. The interesting question would be, what would happen if you went 100,000 miles and then drained and tested the fluid. I would bet it wouldn’t be that same as your cumulative iron number, because the magnet would take a lot of the iron out of solution. That’s the only point I’m trying to make.

Correct, however, your scenario exists in the tests that I have done at this point in time. The magnet is already capturing metal and I have cleaned it every time that I have drained the oil. The magnet would not be cleaned until 100K in your scenario and the magnet would become less effective as the metal builds up--e.g. the magnet will be "full" at some point and the motion of the oil would put some of the metal back into suspension and repeat again.

Totally get that this is not a scientific or standardized test, but speaking for me, the metal is being generated and being detected in the UOA each time, so there is merit to my "method". The point that I was showing is that not all axles wear the same and that early oil changes on a non-pressurized and non-filtered system has advantages. As with everything else, YMMV!

 

[Ray S]

When I serviced the 70HD diff and bearings I realized that it have never been changed by a PO - 65k miles, 51 years.
I had to dig out 1.5" of sludge from the pumpkin with a stir stick and then flush.

Dana has new lubes that are covered by warrantee, "save 1.9% fuel", and up to 500k intervals

Fuel-Efficient Synthetic Gear Lubricants - Lubricants | Spicer Parts

PROBLEM“I’m looking for a lube that does even more than performing in extreme temperatures and protecting the gears and bearings in my rigs.”

spicerparts.com

 

[4WD]

When I serviced the 70HD diff and bearings I realized that it have never been changed by a PO - 65k miles, 51 years.
I had to dig out 1.5" of sludge from the pumpkin with a stir stick and then flush.

Dana has new lubes that are covered by warrantee, "save 1.9% fuel", and up to 500k intervals

Fuel-Efficient Synthetic Gear Lubricants - Lubricants | Spicer Parts

PROBLEM“I’m looking for a lube that does even more than performing in extreme temperatures and protecting the gears and bearings in my rigs.”

spicerparts.com

^^^ Is that 500k intended for class 8 trucks with large capacities ? ^^^

 

[4WD]

You drained and disposed of the fluid, correct. Then you added fresh fluid, ran it for 5,000 miles, then drained and tested it, correct? If so the cumulative iron is a hypothetical number. The interesting question would be, what would happen if you went 100,000 miles and then drained and tested the fluid. I would bet it wouldn’t be that same as your cumulative iron number, because the magnet would take a lot of the iron out of solution. That’s the only point I’m trying to make.

I have pretty much done the same thing on the cheap - Valvoline Dino - white bowl - sunlight
At 18k - just filled with Delvac 1 - will run for a year anyway …
The Rubicon pumpkins shed like a golden retriever Nothing like my GM/AAM axles …

 

[CarbonSteel]

The Rubicon pumpkins shed like a golden retriever Nothing like my GM/AAM axles …

The Dana 44 Advantek axles shed more iron than any I have owned or worked with. With that said, I saw a substantial reduction by REM Isotropic polishing the gears when I re-geared. They are starting to trend like "normal" axles do.

 

[Ray S]

^^^ Is that 500k intended for class 8 trucks with large capacities ? ^^^

I would assume, although the Dana 70HD/80 is pretty large for an RV, and 4qt cap.

 

[law3500]

I usually swap the Factory Fill between 10 and 15 thousand miles. Then I swap every 50k miles after that using the best Synthetic of the proper weight that is readily available to me.

 

[The Critic]

Other than an initial service after 30K, I really don't see a reason to replace it on passenger cars....unless it experiences water contamination. I still change every 60K or so, but it is probably a wallet flush.

 

[wlk]

When I serviced the 70HD diff and bearings I realized that it have never been changed by a PO - 65k miles, 51 years.
I had to dig out 1.5" of sludge from the pumpkin with a stir stick and then flush.

Dana has new lubes that are covered by warrantee, "save 1.9% fuel", and up to 500k intervals

Fuel-Efficient Synthetic Gear Lubricants - Lubricants | Spicer Parts

PROBLEM“I’m looking for a lube that does even more than performing in extreme temperatures and protecting the gears and bearings in my rigs.”

spicerparts.com

Bet that smelled yummy, hate how old diff fluid smells.
Funny story, I made my oldest son change the diff fluid on my old Dakota, it was about 6 yrs old and roughly 50k miles on it. So he pulls the cover and it comes out, gets all over his hands, and then the smell hits him and he starts dry heaving. Hahaha I laughed and laughed - he goes that's not funny dad.. yes it is.

 

[Sequoiasoon]

'19 Pilot Maintenance minder came on at about 10k for the rear diff as initial. I think it's every 25-30k after that but it's not here to check. The couple qts are inexpensive and easy to swap. Keeps me going in beach and trails as well as DD and light towing.

 

[djkurious]

Rear, front diff, and transfer case every 30k in my 03 4runner. 320k on the clock.

 

[Sam_Julier]

1993 240s Dana 30 axle every 10k.

I use any 85W90 or 80W90 GL-5 that meets the SAE J2360 or MIL-L 2105D specifications.

 

[Wheel]

I change the subarus every 30k, front and rear (drain and fill on the tranny too)
They made it easy, so I do it.

 

[Rand]

I usually do the first one early. then a second one at the normal first interval.. then normal intervals.

ie my new subaru will get front/rear around 15k. I'm expecting it to be pretty crusty.
then at 30k.. expect it to be much cleaner
then at 60k.

But it also depends on if I feel like I'm keeping the car 3 years 5 years 10 years etc.

Might just get one at 30k miles.

I do feel the first change is the most important.
Ie I'd rather change at 15k miles then 70k miles vs a 30k and 60k changes

 

[Ray S]

Bet that smelled yummy, hate how old diff fluid smells.
Funny story, I made my oldest son change the diff fluid on my old Dakota, it was about 6 yrs old and roughly 50k miles on it. So he pulls the cover and it comes out, gets all over his hands, and then the smell hits him and he starts dry heaving. Hahaha I laughed and laughed - he goes that's not funny dad.. yes it is.

Don't they all stink? Sulfur-based additives I find stink when new.
Junior does need to learn the hard way, best way.

 

[Rat407]

Every 100k. UOA showed it was still good on my 2002 Silverado that I towed with. Now on my new truck I will do the same.

 

[High Performance Lubricants]

Don't they all stink? Sulfur-based additives I find stink when new.
Junior does need to learn the hard way, best way.

They do not all stink. Ours smells closer to a motor oil than a gear oil. It has worked quite well in the 43 car.