Dave_in_VA

So this weekend, I decide to change the transmission and differential fluid on 05, Z51, MN6 car.

I bought the car at 9K miles, it now has 14K miles. When I bought it the car was all original, down to the OEM tires from the factory (proper date code on them).

Draining and refilling the diff was a pain, but successful. See for how-too info:
The problem was the transmission. After removing the drain and fill plugs, almost no fluid came out of transmission.

Maybe a cup, maybe two. I stuck my finger inside to see if thee was an air bubble or blockage of some kind.

I've never had a single leak from the car.

The car was inspected by a dealer before I bought it. But I do most of my own maintenance and I've had the car for three years. Its problems are mine now.

So I refilled the trans - took almost 4 quarts. I'm going to drive it for 500 miles and change the fluid again.

Hopping for the best.....

ClothSeats

Very interesting. It makes one wonder under what circumstances did the previous owner drain the fluid but not refill. Or, was it just not filled by the factory in the first place? Regardless, how did it make it to 14,000 miles with no oil in it?

Dave_in_VA

The trans draw/fill plugs appeared to have the factory sealant still in place, so possibly no draining. There were three white marks on the fill sticker which I'm guessing we're build marks indicating the original fill occurred.

In talking to Dano523 yesterday, a decent possibility is at some point a trans sensor was replaced and the tech let a lot more fluid drain than desired. And didn't refill the trans.

Fingers crossed that no major damage occurred.

dyerk

You might want to search the forum on how to check the fluid level as the plug is to check the fluid and NOT a drain plug from what I read. If you overfill it you have a good chance of blowing out some seals and causing yourself leaks. I believe to change the fluid you need to drop the pan. Good Luck. Here is a copy from another post:

Service Information
2008 Chevrolet Corvette | Corvette (VIN Y) Service Manual | Transmission/Transaxle | Automatic Transmission - 6L50/6L80/6L90 | Repair Instructions - On Vehicle | Document ID: 1593625
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Transmission Fluid Check
This procedure checks both the transmission fluid level, as well as the condition of the fluid itself. Since the transmission on this vehicle is not equipped with a fill tube and dipstick, a tube in the bottom pan is used to set the fluid level.

Notice: The transmission fluid level must be checked when the transmission fluid temperature (TFT) is between 30-50°C (86-122°F). If the TFT is not within this range, operate the vehicle or allow the fluid to cool as required. Setting the fluid level with a TFT outside this range will result in either an under or over-filled transmission. TFT>50°C=under-filled, TFT<30°C=over-filled. An under-filled transmission will cause premature component wear or damage. An over-filled transmission will cause fluid to discharge out the vent tube, fluid foaming, or pump cavitation.

Observe the TFT using the driver information center (DIC) or a scan tool.
Start and idle the engine.
Depress the brake pedal and move the shift lever through each gear range. Pause for at least 3 seconds in each range. Move the shift lever back to PARK. Ensure the engine RPM is low (500-800 RPM).
Allow the engine to idle for at least 1 minute.
Raise the vehicle on a hoist. The vehicle must be level, with the engine running and the shift lever in the PARK range.



Notice: THE ENGINE MUST BE RUNNING when the trans oil level check plug is removed or excessive fluid loss will occur, resulting in an under-filled condition. An under-filled transmission will cause premature component wear or damage.

Important: Continue to monitor the TFT. If the TFT is not within the specified values, reinstall the trans oil level check plug and repeat the previous steps.

Remove the trans oil level check plug (1) from the transmission fluid pan. Allow any fluid (2) to drain.
• If the fluid is flowing as a steady stream, wait until the fluid begins to drip.

• If no fluid comes out, add fluid until fluid drips out. Refer to Transmission Fluid Fill Procedure .

Inspect the fluid color. The fluid should be red or dark brown.
• If the fluid color is very dark or black and has a burnt odor, inspect the fluid and inside of the bottom pan for excessive metal particles or other debris. A small amount of "friction" material in the bottom pan is a "normal" condition. If large pieces and/or metal particles are noted in the fluid or bottom pan, flush the oil cooler and cooler lines and overhaul the transmission. If there are no signs of transmission internal damage noted, replace the fluid filter assembly, repair the oil cooler, and flush the cooler lines.

• Fluid that is cloudy or milky or appears to be contaminated with water indicates engine coolant or water contamination. Refer to Engine Coolant/Water in Transmission .

Notice: Refer to Fastener Notice in the Preface section.

Replace the trans oil level check plug and tighten to 25 N·m (18 lb ft).
Inspect for external leaks. Refer to Fluid Leak Diagnosis .
Reset the oil life monitor only if the fluid was changed.
© 2009 General Motors Corporation. All rights reserved.

ClothSeats

Dyerk, I think you are under the impression that the OP has an automatic transmission. He states that he has an M6 in the OP.