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I have an 06 auto base with 22k miles on it and 0 modifications.
I got the car with 17k on it and noticed some chatter from the diff when I take a slow turn. So I read to change the fluid. I changed the fluid with Mobil 1 LS synthetic 75w. Did figure 8s and about 100 miles of driving. Still some chatter. So I Took it to Chevy and had them change the fluid. I'm not 100% convinced they did. I think they just put in more additive. So about 3000 miles has gone by and I am still getting the chatter. I drained the fluid to see if anything has been damaged or if I have a bigger prob then I thought.
So I ran a magnet through and the sediment shown is aluminum. Prob from the threads when I stuck my finger in the drain hole.
My question I think is, do I just keep changing the fluid until I get something that works or do I take out the diff and inspect it etc.? Also am I hurting anything by driving in this condition? What are some signs of trouble under normal driving that will indicate it's not just the fluid?
The GM TSB for the diff chatter says to use this. It has worked for the rest of us. Like posted above, do it yourself and use this fluid. You can get it on line for about $25 per quart. No additive required.
Dexron LS Gear Oil 75W-90 does not use an additive. Actually a friction modifier will result in reduced oil performance. The particles in your oil is from but not exclusive to bearing failure. Regardless a tear down and inspection is necessary.
Red Line 75w90 has the friction modifier included. That is what I have used in my cars for 15 years. Putting in my Vette at 1,000 miles when I put the Quaiffe and new gears in 7 years later, the inside of the diff still looked new.
You could have a rear bearing going, but that would not account for the look of the fluid. Rear bearings are harder to check because the axle interferes with rotating it.
I think the shavings are from the drain plug threads. When I shone a light up into the drain I could see at the back end of the hole, metal burs like when you drill a hole and it's burred on the back side. I stuck my finger in and ran it 360 in the hole and that is when the shavings came out. I don't think the shavings were sitting in there and drained out with the fluid.
The metallic atoms in an austenitic stainless steel are arranged on a face-centered cubic (fcc) lattice. The unit cell of an fcc crystal consists of a cube with an atom at each of the cube's eight corners and an atom at the center of each of the six faces. In a ferritic stainless steel, however, the metallic atoms are located on a body-centered (bcc) lattice. The unit cell of a bcc crystal is a cube with one atom at each of the eight corners and a single atom at the geometric center of the cube.
What components of my diff is an alloy with nickel concentration, as well as manganese, carbon and nitrogen, so it is able to maintain an fcc structure making it nonmagnetic.
Honestly, I don't think there is any problem. The Mobil fluid is not a good replacement for the Dexron LS, so I would expect some chatter to continue there. The particles you see are not much and because there is no filter, they have probably been floating around in there since the diff was first manufactured. To me, this is especially likely since they are not magnetic. Yes, some steel is not magnetic, but not the type of steel used in gears and bearings. That steel IS magnetic and so it is not these particles that you are seeing. These particles are likely aluminum leftover from the original manufacture of the diff housing assembly. Bits of soft aluminum like that can't scratch and damage bearings and gears because they are soft and the bearings and gears are, by definition very hard, so to me, they are nothing to worry about.
Honestly, I don't think there is any problem. The Mobil fluid is not a good replacement for the Dexron LS, so I would expect some chatter to continue there. The particles you see are not much and because there is no filter, they have probably been floating around in there since the diff was first manufactured. To me, this is especially likely since they are not magnetic. Yes, some steel is not magnetic, but not the type of steel used in gears and bearings. That steel IS magnetic and so it is not these particles that you are seeing. These particles are likely aluminum leftover from the original manufacture of the diff housing assembly. Bits of soft aluminum like that can't scratch and damage bearings and gears because they are soft and the bearings and gears are, by definition very hard, so to me, they are nothing to worry about.
I changed the fluid and it has been 3 days now. There is 0 chatter in the corners now and it seems to be engaging properly under load. I think it is insane that it is so finicky with the fluid, but now i know ac delco only!
Thanks for anyone who chimed in moral support is always appreciated.
07-02-2015, 05:35 PM
Diff help
