10L1000 Transmission Service Kit with Fluid and Filters

This 10L1000 service kit puts three gallons (12 quarts) of DEXRON-ULV fluid and the DF-434 filter kit in one box for the 2020-2025 Chevrolet Silverado and GMC Sierra 2500HD and 3500HD with the 6.6L Duramax and the ten-speed 10L1000. Owners buy it when a tow-heavy truck is due for its fluid and filter service, when shifts have turned soft or busy after a top-off with the wrong fluid, or when they want the correct ULV fluid and the matching filter without hunting for each piece.

What fluid and filter service does for a 10L1000

The 10L1000 is the heavy-duty member of GM's ten-speed family. It shifts by applying clutches through solenoid-controlled hydraulic circuits in the valve body, so fluid condition and the right fluid viscosity directly affect how cleanly each clutch applies and releases. GM specifies DEXRON-ULV, an ultra-low-viscosity fluid, for every 10L1000 in its 2026 capacities chart (RPOs MKM, MGM and MGU in the 2500/3500 HD). It is not the same as DEXRON VI, and mixing the two changes how the unit behaves. The filter traps clutch material and debris before it reaches the pump and valve body. Towing heats the fluid, and hot fluid breaks down faster, which is why trucks that pull hard deserve the shorter severe-service interval in the owner's manual.

Symptoms that point to a service, and ones that do not

• Fluid that is dark or smells burnt on the dipstick or drain sample
• Soft or delayed shifts after someone topped it off with a non-ULV fluid
• High transmission temperature readings while towing
• Pump whine or delayed engagement when the level is low or the filter is loaded
• Early torque converter clutch apply or the engine dragging down at a stop on 2020-2023 3500HD trucks: Sonnax traces this to a cracked upper valve body casting that ties the TCC circuit to the C clutch circuit. Fresh fluid will not fix that; it needs the later valve body casting.

How to confirm before you service it

Pull a sample and check its color and smell, read the transmission temperature on a scan tool during a normal drive, and scan for codes. Keep in mind the 10L1000 normally launches in 2nd gear and downshifts to 2nd when coasting to a stop, so not feeling a 1st gear launch is normal. Our guides for the light-duty 10L90 fluid type and capacity and flush versus drain and fill explain the same ULV fluid and service choices on the smaller ten-speed, and the 10L90 vs Allison 1000 comparison helps if you are not sure which unit is in your truck.

Fitment

The kit is listed for the 2020-2025 Chevrolet Silverado 2500HD and 3500HD and GMC Sierra 2500HD and 3500HD with the 6.6L Duramax and the 10L1000. The DF-434 filter kit replaces GM 24298004. The kit is listed for the Duramax trucks only, so if your HD has a gas engine or you are not sure which transmission it has, send us your year and VIN and we will confirm before you order. A 2017-2019 HD with the Allison 1000 six-speed takes a different filter and fluid. If you only need the filter, the DF-434 10L1000 filter and pan gasket kit is sold on its own.

Install notes

• Know how much fluid you need. GM lists the 10L1000 fluid change capacity at 13.6 liters (14.4 quarts), and this kit includes 12 quarts. Plan on a few extra quarts of ACDelco DEXRON-ULV so you are not short when you set the level. A full exchange through the cooler lines takes more still.
• Park level, let the fluid cool enough to work safely, and drop the pan slowly; it holds fluid at the rear.
• Install the new filter, clean the pan and magnet, and use the new gasket. Torque the pan bolts evenly in sequence to the factory spec.
• Refill with DEXRON-ULV only, then set the level at operating temperature with the engine running after cycling the selector through each range.
• If the stock pan is damaged or you want a cast replacement while it is off, the 10L1000 cast aluminum deep pan kit bolts on in its place.

Is three gallons enough for a 10L1000 service?

It covers most of a pan drop, but GM lists the 10L1000 fluid change capacity at 14.4 quarts and this kit has 12. Keep two or three extra quarts of DEXRON-ULV on hand so you can finish setting the level.

Can I use DEXRON VI instead of DEXRON-ULV?

No. GM specifies DEXRON-ULV for the 10L1000. It is a lower-viscosity fluid, and substituting DEXRON VI changes clutch apply behavior and shift quality.

Which trucks does this fit?

It is listed for 2020-2025 Chevrolet Silverado and GMC Sierra 2500HD and 3500HD with the 6.6L Duramax and the 10L1000 ten-speed. It does not fit 2017-2019 HD trucks with the Allison 1000 six-speed.

What filter is included?

The DF-434 filter kit, which replaces GM 24298004 and includes the pan gasket. The same kit is sold on its own if you only need filters later.

Will a fluid service fix my truck dragging down at stops?

Probably not. On some 2020-2023 3500HD trucks, Sonnax links early TCC apply and engine drag at a stop to a cracked upper valve body casting. GM strengthened the casting in late 2023. Service the fluid, but have the valve body checked if the complaint remains.

• 10L90 Fluid Type and Capacity
• 10L90 Filter and Pan Service
• 10L90 Flush vs Drain and Fill
• 10L90 vs Allison 1000 Differences