Just a friendly reminder that you may want to service your differential with some fresh gear lube and limited slip additive. Our vehicles are starting to age a bit and this service brings some remarkable results.

I did mine last weekend, it has 60K now on it. I was very surprised at home much it quieted down the noise from the rear end that I thought was solely road noise and it made the differential operation so much smoother.

I used the recommended GM products SAE 75W-90 Synthetic Gear Lubricant (GM Part No. 12378261) and Limited-Slip Differential Lubricant Additive (GM Part No. 1052358).

I first reviewed Toque webpage HERE then went through the procedures in the FSM. I did note the torque values from the FSM were 35 Nm for both drain and fill plugs.

And the FSM said to add 1.69 qts (54 oz) of lubricant first then add the additive, the complete the fill. My observations: make sure you have a rag stuffed under the fill plug, these hand pumps like the one from advanced auto parts...uh sucked it leaked like crazy out of the top of the pump handle, I'd bet 10% loss of product due to this pump that costs 7.95, and it is not easy to squirt that additive in from it's squeeze bottle if you recall the fill hole is on the side! Other than that pretty much a straight forward maintenance items.

I did mine then did the oil change while it was up in the air. It has to be level for oil or differential fluid changes. I did like in the link above, drive up on my ramps and use my low profile jack and a board to raise the rear and put two jack stands under the cradle.

I'm sure a shop would charge at least a hour's labor plus the lubricants. So I'm quite confident I saved a bit of money.

Quiet differential operations...man its sounds and feels like it is new again.

 

Thanks for the reminder. There for a minute I thought you were going to somehow link up Vettes and colonoscopys!

Good point you make about proper maintenance. Thanks

 

I didn't put the additive in this time, I used 1 qt Mobil1 and 1 qt of Tech, that was all I had when I went to get my gear lube off the shelf, both are GL5 products I have no problem so far with a few hundred miles of driving.

My car has about 36K on it and I just picked it up, I didn't like how dark the lube was so I used what I had in the garage.

 

i need to do this soon.

i just need a good pump.

 

An easy method of filling the rear is to use a long piece of tubing and route it out of the wheel well. Take your gear lube bottle and stick the cone shape nozzle into the tubing and squeeze til its empty. Poking a hole in the bottom of the inverted bottle also helps to empty it faster.

 

You don't need a pump just shoot it right out of the bottle, snip off the tip and add a small piece of 3/8" hose and push it right into the fill hole.

 

Thanks for the reminder and info on the fluid needed.

 

Someone at work mentioned the long tube to the wheel well trick as well.

I'm just impressed with the results. I had heard, refresh the fluid to quiet the rear end's down, I just had forgotten how quiet it was when new until now.

Oh and yes that gear fluid is horribly stinky. I think the used fluid was much worst then the new fluid.

...and the 300 mile limit before any full throttle. It was interesting doing the figure 8's, the middle school in my subdivision had a newly paved parking lot with no parking stops installed, made for a perfect area on Sunday to do a whole series of 8's.

 

Thanks for the update. Mark (Toque's) link is a great write-up.

Is this change recommended based on mileage or years? How often?

 

I had a very tiny leaky butt start about a year ago so I did a fluid change with Royal Purple. Awesome. I haven't dripped a drop since and the diff got quieter and smoother. Plus no additive needed for Royal Purple. Whole lot cheaper than dropping the rear to change one crappy seal. I usually balk at any "fluid fixes". I don't believe you can fix a leaky radiator or oil leak with a ????? Brand additive. Those are for people who just don't know any better. But after researching and talking to other c5 owners who had leaky butt- I figured it was worth a try vs. The whole rear end job for 1 defective seal.

It worked.

 

I will be doing this next week when the 3:42's get installed.

 

Did mine while installing the Yank TQ.....definitely a good idea...

 

Thanks I couldn't remember Toque's name to save me when I wrote this.

Owner's manual says falls under Part C: Periodic Maintenance Inspections, which says inspections and service should be performed at least twice a year, then under Rear Axle Service it says to check lubricant level and add if needed. Section 6 gives you illustrated view of how to do the service.

I'm sort of doing it around 50-60K intervals, however I'll probably do the procedure every 50K. Unless someone has better info on this.

 

Royal Purple, mmmum Good! In mine at 79K!

 

I need my rear changed too and my brake fluid it's very dark...!

Changed the trans fluid last winter ...!

 

Just did mine with Amsoil They had a great pump i got for i think 10 bucks

 

Did mine with amsoil as well.
The weekend after I got the car amsoil in the engine, tranny, and diff.

 

Thanks...

Its on my web site at the bottom.
http://mysite.verizon.net/res0aae8/webpage.html

Toque

 

i can never get all the fluid out of the bottle like that.

a pump is the best and easiest answer and the one i will use.

 

Recently did mine with Amsoil and used their pump - no leaks....