14 2 SS Rear Gear fluid change question - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Joe.G · 10-21-2021, 08:09 PM

Hi, I am going to drain my Rear Diff, I have Amsoil 75-90 here to use, I also have GM Limited Slip and Amsoil Limited slip Additive. I understand that the Amsoil has some mixed in from the factory, But I have heard/read mixed reviews on whether or not if I need to add more. If I was to add more should I ad just an oz or two? Or do I fill with out it and se what happens? If I have a issue do i need to drain it down to add an OZ or 2 or is it ok to over fill slightly? Thanks

AlanRubin · 10-21-2021, 10:51 PM

You do not need the additive with gear oil that already has it; which is indicated
on the label. Too much LSD additive can shorten the working life of the oil.

Mobil 1 75W-140 LS gear lube, the additive in it is enough to keep it from chattering.
GM has discontinued the 4 Oz bottles of FM, and replaced it with premixed fluid.

If you change your gear oil every 30k, then you don't have to worry about it.

Joe.G · 10-22-2021, 06:48 PM

Drained it out today and refilled with Amsoil 75-90 no extra additive added, I filled it until it started coming out then Plugged it before it stopped coming out, Figured a little extra would be okay. I don't hear or feel any chattering, The fluid that came out was very dark, and had some metal in it, both Plugs had a lot of sludge, I am glad I did it, would never had thought a low mileage rear would look like that.

AlanRubin · 10-23-2021, 04:23 AM

The BLACK is normal for the first change, that's the carbon coating that is
on the ring and pinion gears. Some metal is okay, just not chunks. The next
time you change the fluid, it should not be that dark, and less mud on the
plugs, and less glitter. LSD should be changed every 30,000 miles.

Joe.G · 10-23-2021, 07:14 AM

Yeah there were no chunks just sludge, I figured since I really didn't flush it out that I would change it again next season then I should be good for longer intervals.

AlanRubin · 10-23-2021, 04:18 PM

Some differentials also have doughnut magnets on the back inside of the back cover
plate. They're not a HARD magnet, they are like a soft rubber magnet, so that
if it falls off, it won't tear up the ring gear. The one in my former Silverado did
that, there were magnet chunks everywhere, but was safe. I brakleen'd it all
out, and replaced it.

The hard doughnut magnets are on the bottom of auto trans pans.

I flushed my 3.27 out, after emptying it, sprayed brakleen in the fill hole, and
drain hole, and let it dry out. It came out brown, and I kept after it will it came
out relatively clear. Filled it back up, and it's been fine. Going to a 3.27 LSD
next week, the whole cradle...

PaulsSS · 10-24-2021, 08:08 PM

Quote:

Originally Posted by AlanRubin

The BLACK is normal for the first change, that's the carbon coating that is
on the ring and pinion gears. Some metal is okay, just not chunks. The next
time you change the fluid, it should not be that dark, and less mud on the
plugs, and less glitter. LSD should be changed every 30,000 miles.

Carbon coating you say? hmmm I've rebuilt probably 100 rears in my time and never seen such a thing as this. Maybe you can post up some info on this "carbon coating". There are aftermarket friction coatings but OEM or OEM replacement gears have no such coatings.

10-21-2021, 08:09 PM	#1
Joe.G Drives: 2014 2SS/RS 6SP Ashen Grey Join Date: Aug 2021 Location: NY Posts: 1,264	14 2 SS Rear Gear fluid change question Hi, I am going to drain my Rear Diff, I have Amsoil 75-90 here to use, I also have GM Limited Slip and Amsoil Limited slip Additive. I understand that the Amsoil has some mixed in from the factory, But I have heard/read mixed reviews on whether or not if I need to add more. If I was to add more should I ad just an oz or two? Or do I fill with out it and se what happens? If I have a issue do i need to drain it down to add an OZ or 2 or is it ok to over fill slightly? Thanks __________________ GM 3.91/TrueTrac OEM ZL1 Rims, Brakes & Side Skirts.ACST4 Splitter/Deflectors NPP M2W,GM Short Throw,Remote Clutch reservoir GPI Ported Rod Mod,BO White PTB,CAI/JRE Scoop, Moroso Catch Can GC Aluminum DS Stainless Works Ceramic LTH/HiFlo Cats SCT X4 Dynosteve, Hotckis 1" Springs & Chassis Max Brace BMR Adjustable Swaybars,Trailing Arms, Adjustable Toe Rod, LCA & Z28 UCA Bushings Hendrix Solid Cradle Bushings Pedders Radius Rod Inserts Strut tower brace Hero Smoked Tail and 3rd Brake Light, Diode Dynamic SL1 Fog Lights AeroForce Dual gauge/Autometer pillar mount.

10-22-2021, 06:48 PM	#3
Joe.G Drives: 2014 2SS/RS 6SP Ashen Grey Join Date: Aug 2021 Location: NY Posts: 1,264	Drained it out today and refilled with Amsoil 75-90 no extra additive added, I filled it until it started coming out then Plugged it before it stopped coming out, Figured a little extra would be okay. I don't hear or feel any chattering, The fluid that came out was very dark, and had some metal in it, both Plugs had a lot of sludge, I am glad I did it, would never had thought a low mileage rear would look like that. __________________ GM 3.91/TrueTrac OEM ZL1 Rims, Brakes & Side Skirts.ACST4 Splitter/Deflectors NPP M2W,GM Short Throw,Remote Clutch reservoir GPI Ported Rod Mod,BO White PTB,CAI/JRE Scoop, Moroso Catch Can GC Aluminum DS Stainless Works Ceramic LTH/HiFlo Cats SCT X4 Dynosteve, Hotckis 1" Springs & Chassis Max Brace BMR Adjustable Swaybars,Trailing Arms, Adjustable Toe Rod, LCA & Z28 UCA Bushings Hendrix Solid Cradle Bushings Pedders Radius Rod Inserts Strut tower brace Hero Smoked Tail and 3rd Brake Light, Diode Dynamic SL1 Fog Lights AeroForce Dual gauge/Autometer pillar mount.

10-23-2021, 07:14 AM	#5
Joe.G Drives: 2014 2SS/RS 6SP Ashen Grey Join Date: Aug 2021 Location: NY Posts: 1,264	Yeah there were no chunks just sludge, I figured since I really didn't flush it out that I would change it again next season then I should be good for longer intervals. __________________ GM 3.91/TrueTrac OEM ZL1 Rims, Brakes & Side Skirts.ACST4 Splitter/Deflectors NPP M2W,GM Short Throw,Remote Clutch reservoir GPI Ported Rod Mod,BO White PTB,CAI/JRE Scoop, Moroso Catch Can GC Aluminum DS Stainless Works Ceramic LTH/HiFlo Cats SCT X4 Dynosteve, Hotckis 1" Springs & Chassis Max Brace BMR Adjustable Swaybars,Trailing Arms, Adjustable Toe Rod, LCA & Z28 UCA Bushings Hendrix Solid Cradle Bushings Pedders Radius Rod Inserts Strut tower brace Hero Smoked Tail and 3rd Brake Light, Diode Dynamic SL1 Fog Lights AeroForce Dual gauge/Autometer pillar mount.

10-21-2021, 10:51 PM	#2
AlanRubin Banned Drives: 2010 LS Join Date: Feb 2021 Location: Pgh Posts: 411	You do not need the additive with gear oil that already has it; which is indicated on the label. Too much LSD additive can shorten the working life of the oil. Mobil 1 75W-140 LS gear lube, the additive in it is enough to keep it from chattering. GM has discontinued the 4 Oz bottles of FM, and replaced it with premixed fluid. If you change your gear oil every 30k, then you don't have to worry about it.

10-23-2021, 04:23 AM	#4
AlanRubin Banned Drives: 2010 LS Join Date: Feb 2021 Location: Pgh Posts: 411	The BLACK is normal for the first change, that's the carbon coating that is on the ring and pinion gears. Some metal is okay, just not chunks. The next time you change the fluid, it should not be that dark, and less mud on the plugs, and less glitter. LSD should be changed every 30,000 miles.

10-23-2021, 04:18 PM	#6
AlanRubin Banned Drives: 2010 LS Join Date: Feb 2021 Location: Pgh Posts: 411	Some differentials also have doughnut magnets on the back inside of the back cover plate. They're not a HARD magnet, they are like a soft rubber magnet, so that if it falls off, it won't tear up the ring gear. The one in my former Silverado did that, there were magnet chunks everywhere, but was safe. I brakleen'd it all out, and replaced it. The hard doughnut magnets are on the bottom of auto trans pans. I flushed my 3.27 out, after emptying it, sprayed brakleen in the fill hole, and drain hole, and let it dry out. It came out brown, and I kept after it will it came out relatively clear. Filled it back up, and it's been fine. Going to a 3.27 LSD next week, the whole cradle...