Rear Differential Fluid Change

So 529 miles into my TRD Off road I changed the differential fluid. I guess the locker rear end has the case that takes the 4.2 quarts, because that's what it took.

And at 529 miles the diff fluid was clean but full of metal flakes that shimmered in the sunshine.

I put in Mobil 1 full synthetic 75w90. I'm going to do the transfer case and front diff too, soon.

When I swapped out to full synthetic in my 2003 at 500 miles, in front, rear and transfer, I went from 20 to 22 MPG's. (4 cylinder/ 5-speed manual.) And I remember changing the rear at 30,000 miles again and the fluid was clear with no metal, looked new actually.

 

I changed mine around 3k. Metal is normal due to gears breaking in

 

Many people here don't recommend synthetic oils for diffs or t case. They report some chatter in the rear especially. I have used Dino oil in mine as a result with no issues.

 

No chatter in 3rd gens. They don't have clutches like the older LSD units

 

Well, in my 2003, everything was 100% for 175,000 miles with Mobil 1 so I'll see how it goes. My 2003 did not have LS, though.

 

I'm waiting until my howl gets addressed

 

Does Toyota know what's causing the howl? Or is everyone still guessing/waiting for an answer? Is it the lockers, or all of them?

 

My howl never started. I'm attributing changing the fluid early to that.

 

idkmybffjill

 

I wonder if switching to a higher viscosity oil (Mobil 1 synthetic 75W-140) might help those with the howl. I'm debating trying it on the basis that the oil might better fill any excess clearances that have developed.

 

Just remember that the locker might not engage as easily and fuel economy will drop

 

Yep. Thats part of the debate.

 

Why not Royal Purple ?
Are you all pulling the cover and brake cleaning everything out then resealing ???

 

Jeeps would not work without the limited slip additive friction modifier.

 

what cover?

 

No cover on a Toyota diff. It's like a ford 9"

 

I noticed when checked my fluid how thin it was. At first I thought it was water. I plan on putting some M1 at 10k.

 

FYI, it's not the wear that causes the differential to howl. My 2nd differential howled the second it was installed. Worse than the first one actually.

Whatever is causing it is either an engineering or a manufacturing flaw.

I'm contemplating putting in some Lucas 85w-140. It's what ECGS recommended when I replaced the howling differential in my 4Runner and that differential is very quiet. I did lose any fuel efficiency either.

 

Do you think it might be a harmonic vibration ?

 

No. I don't think so.