Forum Member’s Corvette Z06 Differential Fluid D.I.Y. Gets the Job Done

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Corvette Differential Fluid Change Items

Corvette differentials don’t need too much maintenance, but doing this once every year or two will your diff turning for a long time.

Many Corvette owners have changed their engine oil or transmission fluid, but it seems that owners of all sorts of performance vehicles often forget about the rear differential fluid. While this fluid doesn’t tend to get dirty as quickly as engine oil or transmission fluid, it does break down over time and when it does, there is less protection for the internal workings of the rear differential.

Of course, you can always pay a shop to change the rear differential fluid, but Corvette Forum member “Dreamin” put together a great write-up showing how to change the fluid in his 2007 Corvette Z06. After you read through the DIY and see how simple it is, the odds are good that anyone who works on their own car will add this project to a list of weekend maintenance items.

C6 Corvette Z06 Differential Diagram

The Introduction

When the OP began his thread on how to change the rear differential fluid in a C6 Corvette Z06, he explained that it took him less than an hour, along with including a list of items needed to attempt the project.

This is a very easy do-it-yourself project… it took me less than an hour. The “quick-disconnect” design GM came up with for the differential cooler line works great.

*** Standard disclaimers apply. I assume no responsibility for any damage. Please be careful – the consequences of a mistake or improper install could be disastrous ***

Pics below are from a 2007 Z06, and a 2007 Service Manual was used.

Tools

  • 3/8” Wrench
  • 10mm Hex Socket (3/8” Hex will work also)
  • Small Flat Blade Screwdriver
  • Oil Drain
  • Suitable Pump / Transfer Tube
  • 3 Quarts Diff Fluid (p/n 88862624 for the GM fluid – NO additive required for this fluid)
  • 1 Diff Cooler Line – Retaining Clip (p/n 24205103). Note: The Service Manual says to use a new Retaining Clip. Most people reuse theirs. However there was a clip failure. So either replace the clip or make sure it is not deformed and fully seated.

Corvette Z06 Diff Plug Clip

Upon first reading this write-up, we found the retaining clip on Amazon and with a price of less than $5, we would recommend that everyone just replace this clip when changing the rear differential fluid. As the OP points out, having that clip fail would be pretty disastrous, so with the part being so inexpensive, it is a good practice to just replace it when you change the fluid.

Draining the Fluid

Removing the fluid from your rear differential is just about as easy as draining your engine oil. Your Corvette Z06’s rear differential has two plugs; a fill plug and a drain plug. To drain the fluid properly, the car needs to be jacked up, but it also needs to be level so that everything drains correctly, meaning that you want to lift all four corners of the vehicle.

Corvette Z06 Plug Diagram

Once the car is in the air, you want to locate the rear differential and on it, you should see the fill plug mounted about halfway up the backside of the case, along with the drain plug on the bottom. It should be noted that some members report that their drain plug is also on the backside of the case rather than the bottom, but in either situation, the process is the same.

Corvette Z06 Differential Fill Plug Open

You start by removing the fill plug, at which some fluid might trickle out, so many sure to be ready with a catch pan. Next, you want to remove the drain plug, but it doesn’t just screw out like the fill plug or like your average engine oil plug. GM used an interesting quick-release fitting, so rather than unscrewing the plug from the case, you actually remove the line running to the plug.

The plug is held in by the clip discussed above and if you bought a new one, you can pry the old one off with a small screwdriver. Once that clip is out, the line running to the plug will simply pull out of the bottom, at which point all of the dirty differential fluid will come flowing out.

Refilling the Fluid

Once the differential is done draining, you re-insert the line going to the drain plug, which pops into place and then is secured by the new clip. From there, you are ready to refill the differential using the pump mentioned in the introduction. You simply pump in fluid until it is up to the fill plug hole and then you tighten the plug, but you aren’t done just yet.

Corvette Z06 Differential Filling

The final step is to drive the car, but GM wants it done in place, so you are to leave the car jacked up, put it in second gear and “drive” 10 miles per hour for one minute with the car in the air. After that, you remove the fill plug, check fluid, add as needed and tighten the plug back up.

Corvette Z06 Liifted

You are done!

Click here to check out the whole how-to write-up or to share your input from changing the fluid in your Corvette Z06 rear differential.

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Patrick Rall is a regular contributor to LS1Tech and JK Forum, among other auto sites.

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