For those of you who are still running the factory installed Differential fluid in your trucks and you have over 1000 miles on them like I did, do yourselves a favor and drain them and install fresh fluid as soon as possible, the reason I'm saying this, is because of all the metal castings I found sticking to the rear drain plug magnet, and that doesn't include the smaller stuff that I caught in the paint filter, which was close to a teaspoon full, none of it was hard gear metal it was all the old stag that was left over when they poured the rear axle housing, the fluid in the rear was really dirty to, then when I pulled the plug on the front I noticed that the fluid was still clear and actually look almost new, but I still caught a small amount of fine metal slag about the size of beach sand, I decided to use Royal Purple in the 75W-140 in both the rear and front, One last thing, the rear took almost 4qts and the front 2qts, which is pretty close to what GM calls for, 3.83 rear & 1.83 for the front, but when I emptied the old fluid into 1 gal jug it just barely filled it, I guess not putting lights in our glove boxes isn't all that GM is trying to cut corners on to save a buck.

Not to mention, and I'm not sure how the new warranty's are with the new trucks, and it hurts me to bring this up(due to the fact it is about a friends "Dodge" pick-up), but he had a hard part break in his rear-end. It was covered under warranty but if he had towed anything prior to this, it would have been a void warranty fix since he did not have synthetic fluid installed(this is per Dodge dealer) in the rear-end, even though the dealer installed his tow package per the request of the buyer.
Perhaps GM or even Ford is doing the same type of things just to try to avoid warranty issues. And yes, this does not even have anything to do with upgrades.
If this is not trying to cut corners to save a buck, I don't know what is.
Mark

Is that why my 'service 4wd' light came on????

Is that why my 'service 4wd' light came on????

not likely. The service 4x4 msg(real common on early 03's) has to do with the encoder motor sensor. Mine has been doing this on and off for about 6 months. I keep trying to get to H-diesel to get it fixed but life always gets in the way.

Things to check though are the connector to see if it's loose, dirty, corroding. More than likely it's a defective motor or sensor.

My neighbor changed the front and rear fluid today in his D/A but used a 50/50 mix of 75W90 and 75W140. He said one was to thin and the other too thick, so half of each is best. Anyone ever hear of that being done?

Oil cocktails are nothing new--lots of guys play organic chemist in their garages. While it certainly shouldn't hurt anything, I'm not so sure he's smarter than all the rest of us.

I run 75-90W in mine, as do most people from what I've seen. I know that 75-140W is popular, but I haven't tried any yet. I'm planning on putting in a diff temp gauge that may sway my decision to go to 75-140W--we'll see.

Do most of you guys that tow heavy run 75-140W?

75-90W, tow @ 22,000 # +/- .

Idahofox

this may be a dumb question but here it is
what would be the problem with a little bit of metal in the differential fluid

this may be a dumb question but here it is
what would be the problem with a little bit of metal in the differential fluid

Bearings, seals, gear lash.......need any more ?

Poor housekeeping !

Idahofox

this may be a dumb question but here it is
what would be the problem with a little bit of metal in the differential fluid

I my case one of the metal slag pieces was just a little smaller then a baby aspirin, it was caught on the drain plugs magnet, but you could tell that it had already got caught between the gears because half of it was flattened, to be honest with you the soft slag doesn't worry me as much as all the casting sand that I found in the drain, for the simple fact that sand is almost as hard as diamonds and it destroy the gears if you don't get it out.

Just got in from changing mine. 1200 miles. Sorta grey and a little sludge on the magnet.

But may I add----BOY DOES IT STINK! Not like your normal rear end juice. Must be a synthetic thing.

I wouldn't deliberately mix viscosities of any lubricant. Pick one or the other. Filthy rear axle lubricant in a relatively low number of miles and low factory fills seem to be the norm in our trucks.

just changed mine this evening with 24000 miles on it. Didnt know about the level being so low from the factory until I found this site.(Thanks Guys!) You should have seen all the sludge and build up on the magnet. The rear axle had about 2 1/2 qts. when I drained it. Took right at 4 qts. before it started to ooze out the fill hole. Replaced it with Leading Edge full synthetic 75w-90.

GM has a advisary letter to the service departments revising the fill level from 4 quarts to 3 quarts due to seals leaking. I am a little hesitant in doing so until I read the letter myself. I here you stick your pinky in the fill hole and bend at the knuckle. when you can touch oil, that's high enough. I got some Royal Purple Max-Gear 75-90 to stick in.

Do you need any special pumps, tools to replace the oil? You use a funnel or what?

3/8" drive ratchet, drain pan, replacement fluid.

NAPA sells a pump that makes it a lot easier.

Idahofox

I believe the service manal states to change you rear diff fluid after the first 500 mile of trailer towing. On the 11.5 axle, which I think we all have, the capacity is 3.83 Quarts. Make sure you are on level ground and fill till level with the bottom of the fill hole. Now all that said I've changed mine anually. I hadn't heard about this advisory letter recomending 3 Q. But last week I had my rear axle seals replaced.....I have been using Mobil 1 75-90 but as the dealer did my seals, I now have the GM grape smelling stuff. I checked the level and although it was not to the fill hole I could touch it with my little finger. Bill W. Did you see the advisory letter. I have heard of a number with seal failures........Bill

Filling to the bottom of the hole will not make anything leak. Most of the sludge you see the first time is clutch disk particles. The second time you change it it will look like new. Later! Frank

Didnt think there were clutches in the Eaton rearend?

When I refilled my rear differential there was about a "nickle sized" mass of shavings and metallic powder. Also, only about 3-qts came out kinda greyish. To refill I got about a 4' piece of 1/2" clear pvc hose and stuck one end into the fill hole and routed it up to the passenger side rear wheel well and squeezed the fluid, 4qts in from above. Much easier on the arms, back, neck than underneath. :ro)

You guys changed your front diff fluid too? Its as nasty if not worse:bleah:

When I did my rear diff I filled it till it came out the hole with Mobil 1 and then jumped on the highway and it proceeded to pump a bunch out the vent tube. Even still now 14,000 miles later it will drip out a little on a really hot day if I am running on the highway. I guess it is time to do it again anyway. I have not looked at the front diff yet.

I had stuff thats look is best described by another member as "baby poo" on the front diff. Just semi sparkly grape juice in the rear.

Baby Poo as in a brownish color? that could be an indication of water. generally grease turns light brown when exposed to water. I wonder what gear lube does when exposed to water.

lol, its not water or the milkshake look, more the goop that comes out on the plug. I dont know all the colors of baby poo since I'm single, I've been led to believe it can be just about any color or combo of colors under the sun so maybe baby poo is a bad analogy:lol:

I was thinking shade as opposed to its consistancy

Crawled under and changed mine last night. I used a pump made by Sta-Lube $7.99. It screwed right on the one quart jugs I bought. Nice, I wouldn't have wanted to try it another way! Mine didn't look too bad actually. Very little sludge on the plug and the viscosity looked fine. I didn't measure the amount that came out but it was certainly more than 2 qts. more like 3.5 to 4 qts. I used Sta-Lube 75-90 synthetic. Oh, and it hadn't been changed with 26,000 miles

There's usually a very yellow "mung" in the front diff- can even be called "golden" it seems to be an assembly lube used by GM. Baby poo is typically a mustard yellow - so Baby Poo is a good analogy.

So what is the proper lube for the front /rear and the transfer case. heard that there was something about color of cap dictates what goes in front....Am new to Chevy and Dmax. got rid of the 03 F250 powerc**** I found it easy finding manuals and stuff for the 6.0l Pstroke but finding it hard to find anything about the Dmax and its workings>

So what is the proper lube for the front /rear and the transfer case. heard that there was something about color of cap dictates what goes in front....Am new to Chevy and Dmax. got rid of the 03 F250 powerc**** I found it easy finding manuals and stuff for the 6.0l Pstroke but finding it hard to find anything about the Dmax and its workings>

Welcome keham,

As for your questions. I use Amsoil 75w-90 front and back, I tow heavy, 22000 +. Trany I run Amsoil ATF.

The issue with the front vent, do a search and you will find Many opinions.

Good Luck, oh helm.com has the books for these trucks, they're pricy but Good.

Idahofox

What if any warranty issues if i go to amsoil? this is a April built 05 3500 srw with dM and i did get gm extended warranty as it was a deal i could not pass on for its cost (free)

thanks
ken

You have the right colored vent, you can run syn up front if you want(I would) I run mobil 1 syn front and back 75 90. as long as it meets or exceeds GM's specs you will be fine.

if your curious about the front breather a search on "white vent" should probably get you some reading but your truck is new enoguh to be good to go

When you service your rear rotate the tires in the air real slow and inspect the teeth on the internal gears that spin the gov lock,mine were broke and i didn't even know it,Smitty

Changed rear diff fluid at 13.6k (yeah I know...) and didn't find anything in the fluid or on the plug that was too alarming. Drained only a little over 2 qts. and refilled with 3.75 qts of GM grape juice (that's some smelly sh*t!) to the tune of $117 & change. Hope it doesn't start venting & leaking...

Recently did my rear diff. and trans. case and this what came out doesn't look like it was full to me. Rear diff is easy to fill with a short piece of hose on the bottle.

What fluids for the auto 4x4 transfer case? had mine done at dealer and they list just ATF but in manual it says atf for manual transfer case and list dur tracII or something close to that name, for the auto 4x4 transfercase. So what is right. apparently dealer not using GM oils list oil as 15w40 axles 75w90 syn no gm part numbers list. bulk drums look like Mobil 1. Now my Ford dealer always used motorcraft named fluids. so now I wonder with them using other name has it got the same additives GM has in theirs. And what about that transfer case. electric auto transfer case list dif fron manual so is ATF ok? Any GM Techs here?.

Another AutoTrac II in the owner's manual question (sigh!) This has been asked and answered a thousand times, but not your fault - it's the crappy description in the stupid owner's manual. The AutoTrac II is only needed in the automatic transfer case only available in 1500 series vehicles. Just because you have dash buttons to select your transfer case does not mean you have an automatic transfer case. The automatic transfer case mentioned in the owner's manual has a large round button at the top that says "Auto" and contains clutches to vary the torque supplied to the front diff. Your transfer case has buttons, but is not automatic, is chain and sprocket and ATF is the correct fluid.

I'll be the non-maintenance whipping boy today. I did have the front changed to synthetic under a TSB and I don't tow a lot. I changed my rear over to Amsoil at 60 count'm 60 thousand miles. No metal, nothing. Made me wonder what all the fuss was about.

After 1000 miles changed front and rear front was yellow and milky rear was fine. Deffinately change them asap
Damn you had a dog in there?? looks pretty good to come out of a tranny

Hello Gang,
I have a 2005 , 2500HD, D/A, SB,CC I want to change the rear end gear oil, will the Amsoil 75-90 be ok or do I need to put an additive with it.
Thanks
Walter:help:

No additive Walter, just the way it comes from the bottle.

Idahofox

As long as it's rated GL-5 you don't need an additive. Mobil 1 is the only synth I've ever used and it is. I would bet all other brands of synthetic are too.

Idle Chatter

Thanks It now makes sense.

No problem, Ken, it's the fault of the owner's manual like I said. Glad to help.