6800 miles 1st diff oil change

[Badbubba]

Decided to change diff gear oil this past weekend since the weather was great and I could do it outside, just incase I made a mess.
6800 miles, approx 20 quarter mile runs, driven moderately aggressive the majority of the time and only taken out in good weather. No mods.
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Captured about 3/4 of quart as it first came out of the drain plug. This is what settled after about 2 hrs. I was surprised the axle lube was only warm after driving 40 miles.


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This is the amount of material captured by the bottom drain plug. Note, there is a smear on the paper towel behind my finger, so it appears the build up sticks out further than it actually does. It had the consistency of aluminum anti-seize. I doubt the bottom drain plug could hold onto any more material. The top fill plug also has a magnet. It retained about 1/4 the amount of material that was on the bottom plug. Both plugs have a "rubber" gasket.


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The new fluids, nice and clear. Bought GM stuff. My belief is that the clutches in the lsd were designed for use with a certain type of lubricant. Similar to some wet clutches in motorcycles which state not to use synthetics, if used, it could allow the clutches to slip. From what I've read, GM uses a group 3 synthetics and Mobil 1, for instance, uses a group 5. Group 5 providing better lubrication, less friction. Btw, the small clear bottle with the white lid is my brake fluid. It was syphoned out with a turkey baster.


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Bought this bottle adapter/filler to transfer the oil into the diff. Got it from the local parts store. Nothing wrong with the filler, just not a good application for the diff. No room. Possibly cutting the capped end of the tube off to allow the tube to go into fill hole deeper may have helped. 2.5 oz of lsd additive per 32 oz of axle lube. I used slightly over 2.0 oz of additive and the complete bottle of axle lube.

[L99SS]

Nice write-up.

So is it possible that using a Group 3 axle lube with 2.5oz of lubricant additive gets it in the neighborhood of say a Group 5 lube?

I'm planning on doing this myself soon. I went and bought the Mobil 1 axle lube, and picked up the little bottle of lube additive from the dealership.

The problem is I still find conflicting details about using different gear oils in the Camaro's LSD. AFAIK, no one has reported any problems or slipping between using brands such as RP, Amsoil, Mobil 1, or OEM. I'm thinking mine could benefit from a lower friction formula as the diff makes rubbing noises when rolling slow with the vehicle turned sharply, like pulling out of the driveway.

The owner's manual states simply to use a 75W-90 LS gear oil, but doesn't caution against group # synths or anything. Is it possible we (I mean like myself, not you Badbubba) are simply over-thinking some of the details a bit?

[Badbubba]

Originally Posted by L99SS

Nice write-up.

So is it possible that using a Group 3 axle lube with 2.5oz of lubricant additive gets it in the neighborhood of say a Group 5 lube?

I'm planning on doing this myself soon. I went and bought the Mobil 1 axle lube, and picked up the little bottle of lube additive from the dealership.

The problem is I still find conflicting details about using different gear oils in the Camaro's LSD. AFAIK, no one has reported any problems or slipping between using brands such as RP, Amsoil, Mobil 1, or OEM. I'm thinking mine could benefit from a lower friction formula as the diff makes rubbing noises when rolling slow with the vehicle turned sharply, like pulling out of the driveway.



The owner's manual states simply to use a 75W-90 LS gear oil, but doesn't caution against group # synths or anything. Is it possible we (I mean like myself, not you Badbubba) are simply over-thinking some of the details a bit?

Thanks, conflicting is correct . If you haven't read the following thread, http://www.camaro5.com/forums/showthread.php?t=198415 , check it out. Ya, nothing to correlate issues with Mobil 1, etc. My concern was having the clutches slip possibly causing a one wheel peel and potentially damaging the spyder gears. I figured if Mobile 1 is more slippery, then less additive would be needed. But how much less? And I didn't feel like experimenting. Although I did alittle, only added slightly more than 2 oz of lsd additive.
http://www.redlineoil.com/product.aspx?pid=41&pcid=4 states add their lsd additive 1 oz at a time until no more chatter. So if replacing with Mobile 1 and adding 2.5 oz of additive is suggested, is this correct for the best performing lsd? Seems to me, if Mobil 1 is a better friction fighter and adding the same amount of lsd additive, then the clutches may slip, which may cause more heat as well. Plus the clutches are already soaked with GM lube, so things could change in the future. We've tested a few lubricants at work for compatability, mainly greases and their bases (urea, esters, soaps, lithium, moly, paraffin) , and the result was not desirable. GM stuff will cost about $40 more, rip off imo. Just my thoughts. Yea, I over think everything.

[TooCool5]

What is the total cost of the G M gear oil & additive?
Why not just clean the magnetic plug and put it back in?

[Andy@AMSOIL]

Little more metal than I would like to see in my diff

[Badbubba]

Originally Posted by TooCool5

What is the total cost of the G M gear oil & additive?
Why not just clean the magnetic plug and put it back in?

GM syn gear lube was around $35, the GM additive was about $13. Then 6% sales tax. A little over $50 total from GM dealership.

If you decide to clean the drain plug magnet, you end up draining the lube out anyway. I can never get all the debris out of my oil catch pan, small rocks, sand, rust, etc. This would contaminate the gear lube. Then the issue of getting the lube back into the diff. Also, the magnet will not attract any non-ferrous material in the lube. In hindsight, I should have placed a magnet in the gear oil that settled in the cut off 2 liter bottle.

[PAUL SS]

FYI... I ran both my old trans and diff fluid through paint strainers and did not find one bit of metal in it

[Andy@AMSOIL]

Originally Posted by Badbubba

GM syn gear lube was around $35, the GM additive was about $13. Then 6% sales tax. A little over $50 total from GM dealership.

If you decide to clean the drain plug magnet, you end up draining the lube out anyway. I can never get all the debris out of my oil catch pan, small rocks, sand, rust, etc. This would contaminate the gear lube. Then the issue of getting the lube back into the diff. Also, the magnet will not attract any non-ferrous material in the lube. In hindsight, I should have placed a magnet in the gear oil that settled in the cut off 2 liter bottle.

I could have done premium synthetic racing proven oils for 40 ish

[Badbubba]

Originally Posted by PAUL SS

FYI... I ran both my old trans and diff fluid through paint strainers and did not find one bit of metal in it

I'm not sure at what micron level a paint strainer filters. It does allow metal flaked paint to pass through it. I don't believe anyone would want metal flake in their gear lube. But at least you have piece of mind, bigger chunks, big problems.

[Badbubba]

Originally Posted by Andy@AMSOIL

I could have done premium synthetic racing proven oils for 40 ish

I am interested in Amsoil for the manual trans. fluid change. PM sent.

[rberns]

I have an appointment with my camaro to put on my solos HF cats and I asked them about changing the rear diff after break in. I have under 1570 miles on mine and they said it is not GM recommended. So should this get done now after my break in or is it a waste of money and I should drive it a bit longer? I don't do any track races either.

[Badbubba]

Originally Posted by rberns

I have an appointment with my camaro to put on my solos HF cats and I asked them about changing the rear diff after break in. I have under 1570 miles on mine and they said it is not GM recommended. So should this get done now after my break in or is it a waste of money and I should drive it a bit longer? I don't do any track races either.

If I had it to do over again. I would have changed it out at 3000 miles. It won't hurt anything if the correct gear oil and amount of additive is replaced. Stating "not recommended" sounds like it would be a bad thing to do. Maybe not required at this time would be a better way of saying it from your shop guys. Section 8-7 of my owner's manual states that the fluid be drained and replaced after every 6 hours of racing or competitive driving. 10-5 of the manual states to change diff fluid at 50,000 for severe service. If this is the most convenient time to change it, do it. Just don't put it off then forget about it. I never changed diff fluid in any of my other vehicles and I put 150,000+ miles on them, never a problem. But I really like this car.

[TooCool5]

Originally Posted by Badbubba

If I had it to do over again. I would have changed it out at 3000 miles. It won't hurt anything if the correct gear oil and amount of additive is replaced. Stating "not recommended" sounds like it would be a bad thing to do. Maybe not required at this time would be a better way of saying it from your shop guys. Section 8-7 of my owner's manual states that the fluid be drained and replaced after every 6 hours of racing or competitive driving. 10-5 of the manual states to change diff fluid at 50,000 for severe service. If this is the most convenient time to change it, do it. Just don't put it off then forget about it. I never changed diff fluid in any of my other vehicles and I put 150,000+ miles on them, never a problem. But I really like this car.

So 50,000 miles for severe service I really don't have to worry about changing diff. fluid. Maybe remove the magnetic plug and hold my thumb over the hole at 25k and clean the debris.

[Markwrench]

For what its worth, my local dealer said GM has been putting the additive in rear diff oil for years. He mentioned a part number change that has a footnote about it. I changed mine with smething under a thousand miles. The old stuff looked terrible and there definitely WAS metal. I don't drive hard so I suspect some of that is casting leftovers, but I wanted it out with all I read here. Used Amsoil Severe Gear and the GM additive. No noises and when I let a little out at like 7500 miles just to see, oil still clean and no particles on the magnet. AMSOIL has never let me down.

As far as synthetics in GM rear diffs, my Tahoe has the Eaton system and GM expressly recommends non synthetic as well as no RTV gasket maker on the cover. It has over 100K on it now with the original bearings and seals and no issues using AMSOIL Severe Gear. I've never felt like the posi wasn't working. Even in 26 inches of snow last year it was a point and go affair to drive.