Rear Diff Factory Fill Come Out Grey Nasty?

[bigjohn]

Quick question.... Everyone keeps talking about how nasty their factory fill looks upon drain.

Could it be that most, if not all, factory fills come loaded with Moly....which is a dark gray looking substance.

At 1000 miles, I drained and replaced the oil on my Honda Shaft Drive VTX1800 and it was a dirty gray, nasty looking stuff. A motorcycle mechanic with with me that day and I said....Wow, look at the horrible condition of this stuff. He said....nope, that's how it should look with all the Moly that is in it.

Thoughts?


.

 

[gathermewool]

Originally Posted By: BigJohn
Quick question.... Everyone keeps talking about how nasty their factory fill looks upon drain.

Could it be that most, if not all, factory fills come loaded with Moly....which is a dark gray looking substance.

At 1000 miles, I drained and replaced the oil on my Honda Shaft Drive VTX1800 and it was a dirty gray, nasty looking stuff. A motorcycle mechanic with with me that day and I said....Wow, look at the horrible condition of this stuff. He said....nope, that's how it should look with all the Moly that is in it.

Thoughts?


.


See page three for the pics and UOA. 1ppm Mo

 

[webfors]

Yeah, definitely not moly in the Subie FF. Maybe it was loaded with teflon

You did have over 300 ppm of Fe. The rear diff only holds .7 quarts in the NA forester. It's not a mystery to me and I wouldn't concern myself too much with the FF. I would start looking forward now that it's gone and UOA your next couple of fills of Motul for comparison.

 

[edhackett]

It's normal for the FF in a Subaru to come out looking very nasty. I've owned two new ones.

I change the diff oil at 2000 miles, 30K, and 30K intervals after that. The 30K change come out looking fine, the 60K comes out looking about like it did when it went in.

Ed

 

[gathermewool]

Originally Posted By: edhackett
It's normal for the FF in a Subaru to come out looking very nasty. I've owned two new ones.

I change the diff oil at 2000 miles, 30K, and 30K intervals after that. The 30K change come out looking fine, the 60K comes out looking about like it did when it went in.

Ed


Based on what I've read your experience seems to be common. I think I'll be safe if I C/O the fluid after 50k, and leave the next fill in for another 400k (optimistic, I know

)

 

[PT1]

Originally Posted By: Kestas
Someone once posted that most of the diff break-in happens in the first 3K. The fluid should be initially changed at 3-5K, then use whatever interval you want after that. I use 30K for regular fluid, 60K for synthetic.


According to some engineers I know at Dana, 95% of diff break-in occurs in the first 500 miles and no towing should occur during that period. Some of the Toyota performance gurus state to only break in with dino 75w90 or 80w90 and change oil at 500 miles with no sustained highway driving more than 30 minutes. 500 to me seems a pretty short interval so I usually change before 3000 miles if possible.

 

[pavelow]

If you tow or in general, abuse your vehicle and/or fall into the severe service category, you should be changing the gear lube (and all other lubes) out sooner than somebody that just loafs around town at the speed limit. The key to a long service life is maintenance.

 

[AdRock]

I always suggest changing the factory fill after the first 5k miles. Get all the break in junk out of there.

Personally, I change the fluid in my trans and rear diff every 25k.

 

[dk1604]

FWIW, the dealership where I purchased my 2005 Impreza RS recommended an early change out of the factory fill differential fluid.