Joining the rear diff club

[DoUSail2]

How many quarts of gear lube are needed do a fluid change?

 

[quakerj]

How many quarts of gear lube are needed do a fluid change?

One quart will do the job for both the PTU and rear diff.

It's actually closer to like 0.83 quarts, you fill until the fluid starts dribbling out the fill hole, you'll have a small amount left over.

 

[94cruiser]

For reference I lik the video again fo the groan noise coming from the diff.
https://www.youtube.com/watch?v=aFhfgxqQUxU

Per factory service manual the troubleshooting states:
First change the fluid, if the noise persists replace the carrier.

 

[G-900879]

If you haven't, change your differential fluid ASAP. I don't care how many miles are on it. Simple to do for a DIY'R

 

[DoUSail2]

The lube arrived today. Does the pinion seal replacement require the fluid to be replaced? Anyone been having leaking pinion seals?

 

[G-143079]

Just wanted to add my experience to the thread for others. Had my rear diff fluid changed at about 80k miles on a 2018 Tour X (red needle). The local shop used valvoline 75w90 full syn. The next day the groaning and noise from the rear end started...low speed turns when starting from a stop primarily. Had to drive it for a few weeks just due to schedule but had them drain the valvoline and replace with the GM recommended fluid. Noise was gone instantly. No new information here but confirming what others have said/encountered.

 

[Undercover87T]

The lube arrived today. Does the pinion seal replacement require the fluid to be replaced? Anyone been having leaking pinion seals?

Mine just started leaking around 57000 miles

 

[DoUSail2]

Mine just started leaking around 57000 miles

Yes, I have oil up on the frame above the pinion seal so I will be replacing mine when I do the lube change. Groan might be from lower level. Looks like I will need to pivot the sway bar down to access the fill plug. Also I hate those two piece driveshafts with the bearing in the middle. Might just take it in to my mechanic. I still don’t have my summer only car running and summer cruise night season is almost over.

 

[Undercover87T]

Yes, I have oil up on the frame above the pinion seal so I will be replacing mine when I do the lube change. Groan might be from lower level. Looks like I will need to pivot the sway bar down to access the fill plug. Also I hate those two piece driveshafts with the bearing in the middle. Might just take it in to my mechanic. I still don’t have my summer only car running and summer cruise night season is almost over.

I have an appointment at the dealer this week to change the trans, PTU and diff fluids including the seal and a couple other things. Carfax says a Valvoline quick lube place changed the PTU and rear diff at 49000 so I'm sure it's got the wrong fluid. No noise though.

 

[Buckjoe]

Yes, I have oil up on the frame above the pinion seal so I will be replacing mine when I do the lube change. Groan might be from lower level. Looks like I will need to pivot the sway bar down to access the fill plug. Also I hate those two piece driveshafts with the bearing in the middle. Might just take it in to my mechanic. I still don’t have my summer only car running and summer cruise night season is almost over.

I use a 10mm Allen socket. I remove the hex from the socket, then use a crescent wrench to turn the Allen hex key.

 

[Buckjoe]

As far as differential lube, I just tried the Valvoline equivalent. Now I know what people are talking about with the moaning. Also, very harsh going from throttle to coast to throttle. Put the nice clean 6k GM product back in before work next morning. All better. I guess it’s worth what it costs. I don’t know what additive pack GM uses….now I’m wondering if the Delco lube is masking an issue the Valvoline exposed, or if the Valvoline just doesn’t cut it. Hoping the former.

 

[HotZ28]

You might want to try some----

LIQUI MOLY Gear Oil (GL4) SAE 85W-90 | 1 L | Gear oil |​

---https://www.amazon.com/gp/product/B004FPP362/?ref_=pe_125775000_1044873430_AGH3Col0502IMG_rtpb_2p_2_lm&pd_rd_wg=42s38&pd_rd_w=UUo6z&pf_rd_p=f1e7cce8-f7fa-4eb4-9109-f0143f124a1a&pd_rd_r=47454cda-2be0-4fa9-9383-42c5602fb6b0&content-id=amzn1.sym.f1e7cce8-f7fa-4eb4-9109-f0143f124a1a

 

[Undercover87T]

I have an appointment at the dealer this week to change the trans, PTU and diff fluids including the seal and a couple other things. Carfax says a Valvoline quick lube place changed the PTU and rear diff at 49000 so I'm sure it's got the wrong fluid. No noise though.

Update on mine. Wasn't the pinion seal leaking and slinging gear oil everywhere, rather the RR axle seal. $400 fix at the dealer. Anyone else have axle seals replaced?

 

[fredzy]

Update on mine. Wasn't the pinion seal leaking and slinging gear oil everywhere, rather the RR axle seal. $400 fix at the dealer. Anyone else have axle seals replaced?

One of my axle seals has been compromised for a long time (not sure when it started, car has 94k miles now) but only weeps slowly so I plan to leave it alone and keep checking every 3 months unless it starts to get worse. No detectable drop in diff oil level in 1 year.

Did they have to drain the diff to replace the seal, do you know?

 

[Undercover87T]

One of my axle seals has been compromised for a long time (not sure when it started, car has 94k miles now) but only weeps slowly so I plan to leave it alone and keep checking every 3 months unless it starts to get worse. No detectable drop in diff oil level in 1 year.

Did they have to drain the diff to replace the seal, do you know?

I wanted the trans, PTU and diff fluids changed so it was getting done regardless. I would imagine yes the fluid should be drained to pull the axle, but not sure. There are 3 bolts and 1 nut on the invoice that get replaced along with the seal.