Teammate Bob B having 2,570 Miles on his 2020 C8 Z51 sent a sample of the used DCT fluid to Blackstone Test labs to analyze and report

Bob has done several hard launches and high RPM drives

Below is their findings :

The test lab will store the analyzed results on file so when Bob sends them other DCT samples as more miles are driven then Blackstone will compare the newest samples with older test samples of Bob's DCT fluid

And then analyze newer sent samples as received and then cross compare with the older samples Bob sends them
Over time, then Bob will be able to see if anything shows degrading before problems occur as Blackstone sends Bob PDF reports and
also maintains results on file for Bob

Here you see their findings and the types of metals seen in this first 2,570 miles driven but in short even with the few miles on this DCT fluid
they recommend the fluid be changed soon to flush out the metals seen now

As you look over what the fluid makeup was in that sample

See there is too much

Iron
Calcium
Phosphorus

As to what the average percentage should be as seen on right side

Testlab explains the makeup of findings

Averages: Both the universal and unit averages are running averages and change with the number of samples we analyze.

Elements: Elements are quantified in the oil at parts per million levels (PPM).
This list shows the most common sources of the elements in manual or automatic transmission oil.
Following each element is a description of where it comes from.
They are grouped by category.

Wear Metals

Aluminum: Housing, bearings, oil pump, gear and vane pumps
Chromium: Ball and roller bearings, alloy of steel parts like gears
Iron: Gears, bearings, shafts, some cases, clutch plates
Copper: Bronze bushings, oil cooler oxides, clutch plates, brass fittings
Lead: Residual gear marking compound, alloy of bronze
Tin: Some bearing cages, alloy of bronze
Nickel: Clutch bands, gear/shaft steel alloy
Silver: Some soft friction bearings, Allison needle bearings
Manganese: Alloy of steel
Titanium: Trace wear metal

Contaminants

Potassium: Antifreeze
Sodium: Antifreeze, additive in some engine oils
Silicon: Airborne dirt, sealers, gaskets, sand-casted parts, and spray lubricants, antifreeze

Oil Additives

Boron
Calcium
Magnesium
Phosphorus
Zinc
Barium

Physical properties

Viscosity/Flashpoint: If a contaminant is present in the oil, the Viscosity and Flashpoint will often be lower than stated in the “Values Should Be” line.
A viscosity reading high or low may show oil oxidation.

Antifreeze %: Indicates the amount of antifreeze found in the oil.
A question mark means we found possible traces of coolant, but not enough to definitively say it’s there.

Water %:
Indicates the amount of water found in the oil.
Insolubles %:
Insolubles are solid materials present in the oil. They are typically free carbon from the oxidation of the oil itself, and accumulated metal in the system.

Bob has done a video to explain his testing of DCT fluid with Blackstone Testlabs



Compare Bob's results when you also do your C8 DCT fluid change

GM DCT service manual flush process :

There are two procedures that must be performed before and after changing the DCT filter. And the level check procedure is correct as well.

Before changing the filter:
Quote:
Hydraulic System Flush Procedure Diagnostic Instructions

• Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis

Description
This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.

The following will occur when the scan tool control is enabled: Engine Speed = 2,000 RPM & Line Pressure = Increase — For 8 min
When to Perform the Procedure
Note: Do NOT perform this procedure unless directed here from another procedure.

Perform this procedure before servicing the component: T12 Automatic Transmission
Conditions for Running the Procedure
• DTCs related to the following system/component = Not Set
o K71 Transmission Control Module
o T12 Automatic Transmission
• Brake Pedal = Applied
• Engine = Running
• Transmission Fluid Temperature Sensor = Warmer than 50°C (122°F)
• Transmission Range = P or N
• Vehicle Speed = 0 km/h (0 MPH)
Reference Information Scan Tool Reference Control Module References
With Scan Tool
Note: Do NOT perform this procedure unless directed here from another procedure.
1. Ignition » On / Vehicle » In Service Mode
2. Select: Module Diagnostics
3. Select: K71 Transmission Control Module
4. Select: Configuration/Reset Functions
5. Select: Hydraulic System Flush Procedure
6. Follow the instructions on the scan tool. The procedure will complete within 8 min
Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification
After the filter change:
Quote:
Hydraulic System Leak Test Diagnostic Instructions
• Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis

Description
This procedure is used to test the transmission for leaks after a repair.

The following will occur when the scan tool control is enabled: Engine Speed = 2,000 RPM & Line Pressure = Increase — For 1 min
When to Perform the Procedure Note: Do NOT perform this procedure unless directed here from another procedure.

Perform this procedure when the following component has been serviced: T12 Automatic Transmission
Conditions for Running the Procedure
• DTCs related to the following system/component = Not Set
o K71 Transmission Control Module
o T12 Automatic Transmission
• Engine = Running
• Transmission Fluid Temperature Sensor = Warmer than 50°C (122°F)
• Transmission Range = P or N
• Vehicle Speed = 0 km/h (0 MPH)
Reference Information Scan Tool Reference Control Module References
With Scan Too
Note: Do NOT perform this procedure unless directed here from another procedure.
1. Ignition » On / Vehicle » In Service Mode
2. Select: Module Diagnostics
3. Select: K71 Transmission Control Module
4. Select: Configuration/Reset Functions
5. Select: Hydraulic System Leak Test
6. Follow the instructions on the scan tool. The procedure will complete within 1 min
Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification
Fluid level check:

Quote:
Transmission Fluid Level and Condition Check
Fluid Level Check Procedure Warning:
The transmission fluid level must be checked when the transmission fluid temperature (TFT) is between 20–40°C (68–104°F). If the TFT is not within this range, either idle or brake torque the vehicle to raise the fluid temperature, or shut off the vehicle to 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 greater than 40°C=under-filled, TFT less than 20°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, possibly causing a fire that may result in serious bodily injury or severe vehicle damage, fluid foaming, or pump cavitation.

1. Start and idle the engine with the A/C turned off.
2. Run the vehicle for 3 to 5 minutes while selecting drive and reverse to fill the clutch circuits.
To properly fill the circuits, place foot on brake, shift into drive for 30 to 45 seconds then shift into reverse for 30 to 45 seconds then repeat.
3. Stop the engine and perform the following actions within 5 minutes after stopping the engine.
4. Raise the vehicle on a hoist. The vehicle must be level with the shift selector in PARK range. Lifting and Jacking the Vehicle
5. Note: To avoid rounding of the transmission oil filler plug, it is recommended using an appropriate 6 point metric socket or wrenches.

Caution:
Use Fuchs TITAN EG FFL-4 TREMEC transmission fluid only.
Failure to use the proper fluid may result in transmission internal damage.

Note:
6. During transmission manufacturing, the fluid is filled by volume and therefore, it could have a fluid level that is approximately 13 mm (0.5 in) below the transmission oil filler plug.
7. If more than 1 liter (1.06 quarts) of fluid drains from the transmission, the transmission may have been previously filled for track use.
8. Note: To avoid rounding of the transmission oil filler plug, it is recommended using an appropriate 6 point metric socket or wrenches.
9. Place a suitable drain pan under transmission.
10. Transmission Oil Filler Plug (1) » Remove — Transmission Oil Filler or Drain Plug Replacement
11. Fill or drain oil until oil level is at the bottom edge of the fill opening.
12. Transmission Oil Filler Plug (1) » Install — Transmission Oil Filler or Drain Plug Replacement