2017 Chevrolet Silverado 3500HD — Coolant Capacity & Type

The 2017 Chevrolet Silverado 3500HD holds between 16.8 quarts and 30 quarts of coolant depending on which engine it is equipped with. As an ASE-certified master technician, I can tell you that keeping the cooling system on these heavy-duty workhorses maintained is critical, whether you are hauling a loaded gooseneck trailer across the country or just driving to the job site. Below is the complete breakdown of the coolant capacity, type, and maintenance procedures for your 2017 Silverado 3500HD.

Quick answer

• Total cooling system capacity: 16.8 quarts to 30.0 quarts (15.9 L to 28.4 L) depending on the engine and auxiliary heater options.
• OEM coolant spec: DEX-COOL (Orange). This is an OAT (Organic Acid Technology) formula meeting General Motors specification GMW3420 (formerly GM 6277M).
• Mix ratio: 50/50 mixture of DEX-COOL concentrate and clean, distilled, or deionized water. You can also purchase pre-mixed 50/50 DEX-COOL. In extreme cold climates (below -34°F), a 60/40 coolant-to-water mix may be used, but never exceed 70% coolant.

Capacity by engine option

The 2017 Silverado 3500HD comes with two primary engine options: the standard 6.0L Vortec V8 gas engine and the 6.6L Duramax V8 turbo-diesel (the L5P engine introduced for 2017). Capacities can vary slightly based on cab size and dual alternator or auxiliary heating setups.

Note: Always verify your level at the surge tank after a complete drain and refill, as you will rarely get 100% of the old fluid out during a standard drain.

Flush interval

General Motors recommends replacing the DEX-COOL engine coolant every 150,000 miles or 5 years, whichever comes first, under normal driving conditions.

However, heavy-duty trucks are rarely used for "normal" driving. If your truck is subject to severe duty—which includes frequent heavy towing, high-idle times, driving in dusty environments, or extreme ambient temperatures—I strongly advise draining and filling the coolant every 75,000 miles or 3 to 4 years. Over time, the OAT inhibitors in DEX-COOL break down. If left in the system too long or exposed to air from a leak, it can form a thick sludge that will severely damage the cooling system.

How to refill & bleed

The Duramax engine, with its EGR coolers and large heater core network, is notorious for trapping air. A vacuum-fill tool is highly recommended.

1. Drain the system: With the engine cold, remove the surge tank cap. Open the radiator drain petcock (located at the bottom corner of the radiator) and drain into an appropriate pan.
2. Vacuum fill (Recommended): Hook up a pneumatic vacuum cooling system filler to the surge tank. Draw a vacuum on the system to collapse the hoses (this tests for leaks and evacuates air). Open the valve to draw your 50/50 DEX-COOL mix directly into the system until full.
3. Manual fill (If vacuum tool is unavailable): Add the 50/50 DEX-COOL mix to the surge tank up to the "Cold Fill" line. Leave the cap off.
4. Run and bleed: Start the engine and turn the cabin heater to maximum heat and the blower on low. This ensures the heater core valve is open. Let the engine idle until it reaches operating temperature and the thermostat opens (you'll feel the upper radiator hose get hot).
5. Top off: As the thermostat opens, the coolant level in the surge tank will drop. Slowly add coolant to keep it at the cold fill line. Once the level stabilizes and no more air bubbles appear, install the surge tank cap tightly.
6. Test drive: Drive the truck, let it cool down completely, and recheck the level. Top off as needed.

Common cooling system issues

For the 2017 Silverado 3500HD (part of the GMTK2XX generation), there are a few specific cooling system issues to watch for:

• Water pump failure (Duramax L5P): While improved over previous generations, the L5P can still experience premature water pump seal leaks. Check for a slow orange drip at the front of the engine or the smell of burning coolant.
• Radiator crimp leaks: The plastic end tanks on the radiator are crimped to the aluminum core. After years of thermal cycling, these crimps can loosen, causing slow, weeping leaks.
• DEX-COOL sludge: If conventional green (IAT) coolant is accidentally mixed with the factory DEX-COOL, it creates a thick, muddy sludge that will clog the heater core and radiator. Always stick to OAT-compatible DEX-COOL.
• Surge tank cracking: The pressurized plastic surge tank is exposed to intense underhood heat and can develop hairline cracks, leading to mysterious coolant loss and overheating.

If you suspect a coolant leak or need a professional flush on your heavy-duty truck, don't put it off. Find a trusted shop on Repairius.