Nasty front differential oil..

[JTK]

Today I dumped and refilled the front diff on my 2005 trailblazer LS @ 22Kmi. I know color is not necessarily an indication the lube is shot, but man was it black! It almost looked like it had graphite in it. The dark stuff would kind of settle out if you let it sit long enough. There's no magnet on the drain bolt. Just a bolt with a heavy nylon washer. I refilled it with Mobil-1 75w-90. Capacity per my manual is 1.7pts which is just shy of a quart. I used a thumb trigger oiler can to refill, man did my fingers get worn out. It's got a HUGE fill port, so refilling really is not that bad. $9.99 for a qt of M1 gear oil & about 30min & she's done. I wanted to get at the rear diff tonight but I forgot to p/up a can of brake cleaner to clean the mating surfaces for proper RTV-ing.

Joel

[ September 14, 2006, 09:35 PM: Message edited by: JTK ]

 

[cfromc]

I bet the next time you drain it, it won't be that bad. It was breaking in and it was conventional fluid. That's probably why it was nasty.

 

[gtx510]

Maybe the OEM fluid had a ton of moly in it?
You don't need brake cleaner to clean the diff cover, dish soap will work just about as well. Kitchen degreaser, windex, acetone, paint thinner (might leave a residue?), will all work.
Just saving you a trip to the parts store.

Does it bother anyone else that M1 now costs more than RL, RP, Amsoil, etc?

 

[JTK]

Supposedly the factory installed stuff is synthetic 75w-90 front and rear (auto-trak II for the middle). Thanks for the tip on the pre RTV cleaning. I dont want to loose any of that $9.99/qt M1 liquid gold!!! It's the only 75w-90 pepboys had aside from a lucas brand that was the same price. Local wally world had no 75w-90 avail.

Joel

 

[LargeCarMan]

I drained mine at 10hours and it had quite a bit of metal break-in material in it. The best thing anyone can do in a new componet is R&R the Diffie oil as quick as possible. Few hours in a motorcycle or ATV about 5K on trucks, cars, etc...that also goes for transaxles, manual tranny's etc.

 

[01rangerxl]

The first fill will always be kind of nasty.

I first changed mine at 50K (manual says to at 150K). It was dark gray and just plain nasty. The current synthetic fill from the last change still looks new.

 

[Jim 5]

In all the 4x4's I've ever owned, the front diff fluid always looked worse than the rear. (Toyota 4runner, '69 Bronco, '98K1500).

I think one of the reasons is that the front diff gets used about 1% (or less) of the time. As a result, It never heats up and burns off the condensation it collects over time. I've often thought of using the cheapest diff fluid in the front, and a good synthetic in the back. Then I'd change out the front fluid twice as often as I did the rear.

This will be my approach from now on...when I buy another 4x4 here shortly. I also agree with changing out the fluid early and often at first from new.

 

[Colt]

The front Diff on my Explorer had nasty greenish colored fluid at 15K.Ford uses synthetic fluid.
I went with Amsoil Severe Gear in both Diffs.

 

[fixit301]

Hey JTK,
I think we have the same truck! I did the front and rear diffs about 2 weeks ago. I had almost 11000 miles...and the stuff looked horrible. I used a homemade fluid extractor and sucked from the "fill" on the rear diff. Ended up using Royal Purple gear oil. I used the GM Autotrac II for the xfer box. Overall not that bad of a job.

 

[mdv]

quote:

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Originally posted by gtx510:
Does it bother anyone else that M1 now costs more than RL, RP, Amsoil, etc?

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Just helps me sell more oil!

 

[JTK]

quote:

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Originally posted by fixit301:
Hey JTK,
I think we have the same truck! I did the front and rear diffs about 2 weeks ago. I had almost 11000 miles...

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Fixit- so you didn't pull the rear diff cover? I'm trying to figure out if I should get another gasket, or use the permatex "premium black" RTV I have. Looks like she's got a gasket from the factory.

Kinda unsual for me since most seem to use RTV alone these days. I prefer RTV for diffs, but hesitate to go non OEM since I'm still under 3/36.

Joel

 

[fixit301]

Thats right.. I went the easy route. I didn't take off the rear cover. I just "sucked" it out and replaced with new. A whole lot less mess involved.