2017 Chevrolet Silverado 2500HD Coolant Capacity & Type Guide

The 2017 Chevrolet Silverado 2500HD holds between 17.4 and 31.4 quarts (16.5 to 29.7 liters) of coolant, depending on whether it is equipped with the 6.0L gas engine or the 6.6L Duramax diesel, as well as auxiliary heating options. Maintaining the cooling system on a heavy-duty truck like the Silverado 2500HD is critical, especially if you regularly tow heavy loads or operate in extreme temperatures.

As an ASE-certified master technician, I always stress the importance of using the correct coolant type and maintaining proper fluid levels to prevent catastrophic engine failure. Here is your comprehensive guide to the 2017 Chevrolet Silverado 2500HD cooling system.

Quick answer

• Total cooling system capacity: 17.4 to 31.4 quarts (16.5 to 29.7 liters) depending on engine and options.
• OEM coolant spec: DEX-COOL (Orange). This is an OAT (Organic Acid Technology) coolant meeting GM specification GMW3420.
• Mix ratio: 50/50 mixture of DEX-COOL concentrate and clean, drinkable water (distilled or deionized water is highly recommended to prevent mineral buildup), or a 50/50 pre-mixed DEX-COOL solution.

Capacity by engine option

Because the 2500HD is built for various duty cycles, its fluid capacities vary significantly between the gasoline and diesel powertrains. The 2017 model year marked the introduction of the L5P 6.6L Duramax, which has a massive cooling system to manage the heat generated by its high torque output.

Note: Capacities are approximate. Always fill to the "Cold Fill" line on the surge tank and adjust after bleeding the system.

Flush interval

General Motors uses extended-life DEX-COOL, which is designed to last a long time, but it isn't a "lifetime" fluid.

• Normal Duty: Flush and replace the coolant every 150,000 miles or 5 years, whichever comes first.
• Severe Duty: If you frequently tow heavy trailers, idle for extended periods, or drive in dusty/extreme environments, consider dropping this interval to 100,000 miles or 4 years. Over time, the OAT anti-corrosion additives break down, which can lead to sludge formation and degraded cooling performance.

How to refill & bleed

Properly bleeding the air out of the cooling system is essential. Air pockets can cause localized overheating and erratic temperature gauge readings.

1. Drain: Ensure the engine is completely cold. Place a drain pan under the radiator drain petcock and empty the old coolant.
2. Locate the bleed screw (Duramax L5P): On the 6.6L Duramax, locate the coolant bleeder valve near the thermostat housing. Opening this helps evacuate air as you fill. The 6.0L gas engine typically relies on the surge tank to self-bleed, though a vacuum-fill tool is the professional standard for both.
3. Fill: Close the radiator drain. Slowly pour the 50/50 DEX-COOL mixture into the surge tank. If bleeding the Duramax, close the bleeder valve once a steady stream of coolant (without bubbles) flows out. Fill the surge tank up to the "Cold Fill" mark.
4. Circulate: Leave the surge tank cap off. Start the engine and turn the climate control heater to the maximum heat setting with the fan on low. This opens the heater control valve and pushes coolant through the heater core.
5. Idle and top off: Let the engine idle until it reaches operating temperature (the upper radiator hose will become hot). You will likely see the coolant level in the surge tank drop as the thermostat opens and air escapes. Slowly add more coolant to maintain the level.
6. Seal and recheck: Install the surge tank cap tightly. Drive the vehicle for a few miles, let it cool down completely, and check the level again. Add fluid as necessary.

Tech Tip: For heavy-duty trucks with massive cooling capacities like the Duramax, I strongly recommend using a pneumatic vacuum-fill tool. It pulls a vacuum on the entire system, allowing you to draw the new coolant in without introducing any air pockets.

Common cooling system issues

For the 2017 generation of the Silverado 2500HD, keep an eye out for a few known cooling system weak points:

• Water Pump Failure: On the 6.0L gas engines, the water pump bearings can begin to wear out around 100,000 miles, leading to a slow weep from the pump's weep hole. The Duramax water pump is more robust but will eventually require replacement; look for signs of orange crust around the pump housing.
• Heater Core Quick Disconnects: The plastic quick-disconnect fittings at the firewall (connecting the heater hoses to the heater core) become brittle due to heat cycling. They are notorious for cracking and causing sudden coolant leaks.
• Radiator End Tank Leaks: The factory radiator utilizes an aluminum core crimped to plastic side tanks. Over time, the crimp seals can fail, resulting in a slow loss of coolant down the sides of the radiator.

If you suspect a leak, notice a sweet syrup-like smell, or see your temperature gauge creeping past the midpoint, don't ignore it. Heavy-duty engines are expensive to replace, and a simple coolant leak is usually straightforward to fix.

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