2024 Chevrolet Silverado 2500HD Fluid Specifications Guide

As an ASE-certified master technician, I’ve seen firsthand how a wrong fluid choice can cause catastrophic damage, especially on heavy-duty trucks built for towing and hauling. If you are servicing a 2024 Chevrolet Silverado 2500HD—whether it’s equipped with the 6.6L gas V8 or the legendary 6.6L Duramax diesel—using the exact factory-spec fluids is non-negotiable.

Below is the definitive fluid specifications guide for the 2024 Chevrolet Silverado 2500HD, compiled for Repairius.com to keep your heavy-duty rig running at peak performance.

Quick reference

Note: Capacities are approximate and can vary slightly based on specific build codes or cooling packages. Always verify in your owner’s manual or OEM service info and check the level on a level surface after filling.

Fluid	Type/Spec	Capacity
Engine Oil (6.6L Gas)	5W-30 (GM dexos1 Gen 3 / API SP)	8.0 qts (7.6 L)
Engine Oil (6.6L Diesel)	15W-40 or 5W-40 (dexosD or API CK-4)	10.0 qts (9.5 L)
Engine Coolant	Dex-Cool OAT (GM Spec GMW3420)	Gas: ~18.2 qts / Diesel: ~27.8 qts
Transmission Fluid	DEXRON ULV (Allison 10-Speed)	~11-12 qts (Pan drop/filter change)
Transfer Case (4WD)	DEXRON VI ATF	1.6 qts (1.5 L)
Front Differential	75W-90 Synthetic Gear Oil	~1.5 qts (1.4 L)
Rear Differential	75W-90 Synthetic Gear Oil	~3.0 - 3.5 qts
Brake Fluid	DOT 4 Hydraulic Brake Fluid	Fill to MAX line
Power Steering Fluid	GM Power Steering Fluid (P/N 19329450)	Fill to MAX line
DEF (Diesel Only)	Diesel Exhaust Fluid (ISO 22241)	~7.0 gallons
Washer Fluid	Standard Automotive Washer Fluid	~1.5 gallons

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Engine Oil

6.6L L8T V8 (Gas)

For the 6.6L gas engine, GM mandates a 5W-30 viscosity engine oil that meets the dexos1 Gen 3 specification (which supersedes Gen 2 and API SP). The dexos1 Gen 3 specification offers improved protection against Low-Speed Pre-Ignition (LSPI) and better deposit control. Expect to use about 8 quarts with a filter change. Interval: Follow the Oil Life Monitor (OLM), but never exceed 7,500 miles or 12 months under severe duty (towing, hauling).

6.6L L5P Duramax V8 (Diesel)

The Duramax requires heavy-duty diesel engine oil. For ambient temperatures above 0°F, use 15W-40. For colder climates (below 0°F), you must step down to a 5W-40 full synthetic. Crucially, the oil must meet the dexosD or API CK-4 specification. Pitfall: Never use older CJ-4 or CI-4 oils, as they do not have the proper ash content limits required to keep your Diesel Particulate Filter (DPF) from clogging prematurely.

Engine Coolant

Both engines require Dex-Cool (GM Spec GMW3420), which is an Organic Acid Technology (OAT) coolant. It is typically orange in color. Pitfall: Never mix Dex-Cool with traditional green (silicate-based) or HOAT (Hybrid Organic Acid Technology) coolants. Mixing coolant types causes chemical drop-out, turning the coolant into a thick, muddy gel that will quickly clog the heater core and engine water jackets, leading to severe overheating and engine block damage. Always mix concentrated Dex-Cool 50/50 with distilled water, or buy a pre-mixed jug.

Transmission Fluid

For 2024, both the gas and diesel engines are mated to the heavy-duty Allison 10-speed automatic transmission. This transmission requires DEXRON ULV (Ultra-Low Viscosity) automatic transmission fluid. Pitfall: DEXRON ULV is not backwards compatible. Do not use DEXRON VI, ATF+4, Mercon LV, or "universal" multi-vehicle transmission fluids. Using anything other than ULV will cause incorrect clutch engagement, overheating, and eventual transmission failure.

Transfer Case & Differentials

Transfer Case

If your 2500HD is 4WD, the transfer case takes DEXRON VI ATF. Even though the transmission takes ULV, the transfer case must use DEXRON VI. Change this fluid every 45,000 miles if you frequently tow or use 4WD, as the chain and planetary gears shear the fluid rapidly under heavy loads.

Front and Rear Differentials

Both differentials call for a 75W-90 Full Synthetic Gear Lubricant (GM Part Number 88863089 or equivalent). Note on Additives: The GM heavy-duty rear axles (American Axle Manufacturing, typically the 11.5" or 12.0") utilize a G80 mechanical locking differential. This unit is designed to operate on pure synthetic 75W-90 gear oil without any friction modifiers or Limited Slip Differential (LSD) additives. Adding an LSD friction modifier can actually cause the locking mechanism to slip and fail to engage properly.

Brake & Power Steering Fluids

• Brake Fluid: The 2500HD utilizes a heavy-duty hydraulic braking system that requires DOT 4 Brake Fluid. DOT 4 has a higher boiling point than DOT 3, which is critical when towing heavy loads down steep grades. Flush the brake fluid every 2 to 3 years to prevent moisture buildup, which lowers the boiling point and rusts internal ABS module components.
• Power Steering: The heavy-duty steering box utilizes GM Power Steering Fluid (Part No. 19329450). While some older trucks used ATF, stick strictly to the GM hydraulic power steering fluid specification to protect the seals in the steering gear and hydro-boost system.

Diesel Exhaust Fluid (DEF)

If you drive the Duramax, you must maintain your Diesel Exhaust Fluid. The system requires DEF meeting the ISO 22241 specification. Pitfall: DEF has a shelf life. It degrades quickly in extreme heat and direct sunlight. If you buy DEF in a jug, check the date code. Never put old or contaminated DEF into the 7-gallon tank, as replacing the DEF injector and NOX sensors due to bad fluid can cost thousands of dollars.

Maintaining a heavy-duty truck is all about sticking rigidly to the specifications. If a service job is outside your comfort zone, don't risk your rig. Find a trusted shop on Repairius.