How often do you change rear diff fluid

I changed it on my 3500s at 5,000 miles and it was pretty dark, presumable with wear metals, then again after another 10,000 miles. The fluid is pretty clean after the second change, so I put in HPL 75w-90 and will sample it after 30,000 miles on the fluid and decide from there. These differentials are so strong, there is little reason for them to wear, unless the factory fluid is run with all the wear-in metal.
 
Unless you are driving your truck in severe conditions, every 15k miles does sound like overkill. I change the front and rear diff fluid in my wife's Outback every 30k, and that seems to be more frequent than needed. We don't go off road that often. I changed the fluid in my E350 at 50k, and plan on staying with that interval.
 
I changed it on my 3500s at 5,000 miles and it was pretty dark, presumable with wear metals, then again after another 10,000 miles. The fluid is pretty clean after the second change, so I put in HPL 75w-90 and will sample it after 30,000 miles on the fluid and decide from there. These differentials are so strong, there is little reason for them to wear, unless the factory fluid is run with all the wear-in metal.
The first change on the Outback was very dark also. But I found out that Subaru uses a factory fill with a huge dose of moly. So that accounted at least for part, if not all of why the first change was so dark. Every change after that has looked almost as good coming out as it did going in.
 
Whenever Acura maintenance reminder comes on in our SH-AWD vehicles. I think I have done three changes in 100K miles. Usually it's not dirty at all coming out and not much metal debris on the drain plug magnet. Very easy to do at home DIY and costs less than $50 in OEM fluids and crush washers.
 
The Canyon does no real work beyond grocery-getting, and I like knowing the LS diffs in the Mustangs are being kept healthy, so all three vehicles get the diffs dumped every 30K (the convertible only has 15K on it, so it hasn't been touched). There has been quite enough black sludge attached to the magnets at that mileage, and I like to trade out OEM fills for Redline in the diffs.

Pretty interesting that any manufacturer is calling for 15K. Personally, I'd put a really good fluid in, and leave it til 30K.

This is what I find on the interwebs.

Screenshot 2022-04-16 110442.jpg
 
I changed it on my 3500s at 5,000 miles and it was pretty dark, presumable with wear metals, then again after another 10,000 miles. The fluid is pretty clean after the second change, so I put in HPL 75w-90 and will sample it after 30,000 miles on the fluid and decide from there. These differentials are so strong, there is little reason for them to wear, unless the factory fluid is run with all the wear-in metal.
What did you use for the first 2 changes before putting in the hpl diff life?
 
My owners manual on my new to me 06 RAM had 15,000 miles. That seem kind of crazy to me. How often do you change your rear end fluid?
I have gone 30k with no issues on my 2008 Jeep but mostly go 15k because it has drain plugs on the diffs and is easy. I do 15k on the 18 and 21 Jeeps. I run 75w140 synthetic in both ends because that's what Dana recommends. I've run Mobil 1 for the longer distances but also Supertech and Valvoline. I like Valvoline lately because it comes in bags.
 
If the vehicle has an easy drain plug, I try and remember every 20k. Then again, I had a rear end fail because it was contaminated with water from the PO. Apparently he was launching boats frequently.
 
My 2005 Chevy Avalanche with the G80 bought used 8 years ago and at 162,000 miles, I changed the FF at 210,000 miles with Delvac1 and the old oil looked pretty good for so many miles. I doubt I’ll ever change it again.
 
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