Diff fluid change interval

[f5fstop]

Originally Posted by wannabeH3

all h3's have 4 year 50k miles. even if you bought yours when it was 3/36 they changed it to 4 50

But '07 vehicles have a 5 yr/100K powertrain that incudes axles.

[Hal]

f5fstop,
Shouldn't we be concerned that many of us are finding a significant difference in the condition of the rear diff fluid compaired to the front diff at 10K miles or less?
And how many folks have twice or three times as many miles and have never checked theirs??

[f5fstop]

Does black fluid mean the fluid is bad? Only way to tell is an oil analysis, and I don't believe anyone has done that.

[Hal]

Originally Posted by f5fstop

Does black fluid mean the fluid is bad? Only way to tell is an oil analysis, and I don't believe anyone has done that.

OK, next time if the fluid is black I'll taste it to be sure it's bad

f5, I understand your point, I'm just still a bit curious...

It's not a question of the FLUID being good or bad... more to the point: what is going on in the REAR diff to make it black and have alot more metal fragments stuck to the magnet on the drain plug as compaired to the FRONT. I haven't seen that in any of my other 4x4 vehicles.

Has anyone changed it a second time and found the same thing?

[f5fstop]

Originally Posted by Hal

OK, next time if the fluid is black I'll taste it to be sure it's bad Make a comparison test with the front diff fluid.

f5, I understand your point, I'm just still a bit curious...

It's not a question of the FLUID being good or bad... more to the point: what is going on in the REAR diff to make it black and have alot more metal fragments stuck to the magnet on the drain plug as compaired to the FRONT. I haven't seen that in any of my other 4x4 vehicles.
Did a magnetic drain plug show a lot of metal, or just a covering of metal on the plug? The breaking in process will result in some metal particles. Why it is darker, probably has something to do with the rear has more stress to it then the front. I guess we would need a chemical engineer to step in and explain that one.

Has anyone changed it a second time and found the same thing?

[Hal]

Originally Posted by f5fstop

did the drain plug show a lot of metal

There was a lump of ferrous sludge convex on the rear drain plug about equal in size to a plain m&m candy (but it didn't taste as good), in other words there was a pretty good size blob stuck to the plug, but no big chunks luckily. The front plug had a healthy coating but not what I would call a blob like the rear had.
Is that just the breaking in of the diff? or could there be a materials issue with some of the metal in there?
I guess time will tell. And yes, I'm getting a little tired of this topic myself. So, we'll just have to revisit it in 10K miles.