2015 Ford F-350 Super Duty Coolant Capacity & Type

The 2015 Ford F-350 Super Duty can hold between 21.1 and 39.8 quarts (20 to 37.7 liters) of coolant, depending on the engine and cooling configuration.

Quick Answer

• Total Cooling System Capacity: 21.1–39.8 qts (20–37.7 L) - Varies by engine & single/dual radiator setup.
• OEM Coolant Specification: Ford Motorcraft Orange Antifreeze/Coolant (Color: Orange, Chemistry: OAT - Organic Acid Technology)
• Ford Specification Number: WSS-M97B44-D
• Mix Ratio: 50/50 with distilled water (pre-mixed or concentrate)

Capacity by Engine Option

The 2015 F-350 was available with two very different engines, leading to significant variations in cooling system capacity. The diesel engine, in particular, could be had with a single or dual radiator setup, which greatly impacts the total volume.

Flush Interval

Following the correct flush and fill interval is crucial for protecting the engine from corrosion and overheating.

• Normal Service: The initial flush is recommended at 6 years or 100,000 miles. Subsequent flushes should be performed every 3 years or 50,000 miles.
• Severe Duty: For trucks that see heavy towing, frequent idling, or operate in dusty conditions, it is wise to shorten the interval. Consider a flush every 30,000 to 45,000 miles to ensure maximum cooling system protection.

How to Refill & Bleed

Properly refilling and bleeding the air from the cooling system is critical, especially on the complex Power Stroke diesel engine.

1. Mix Coolant: If using concentrate, mix it 50/50 with distilled water before pouring. Do not use tap water, as its mineral content can cause scaling and deposits.
2. Slow Fill: Add the coolant slowly to the degas bottle (expansion tank). This helps minimize the amount of trapped air.
3. Bleeding the 6.7L Power Stroke: This engine has a primary and a secondary cooling system. It is highly recommended to use a vacuum-fill tool (like an Airlift) to ensure no air pockets are left behind. Air pockets can lead to persistent overheating issues.
4. Bleeding the 6.2L Gas: While less complex, a vacuum-filler is still the preferred professional method. If not available, you can use a spill-free funnel kit. Attach the funnel to the degas bottle, fill it partway, and run the engine with the heater on high. This will help purge air as the thermostat opens. Let the engine cool completely before topping off.

Common Cooling System Issues

This generation of Super Duty trucks has a few known issues to watch for:

• Radiator Leaks: Both the primary and, if equipped, secondary radiators can develop leaks from the end tanks or seams, often visible as orange-colored crust or drips.
• Degas Bottle Leaks: The plastic degas bottle (coolant reservoir) can become brittle with age and develop hairline cracks, leading to slow coolant loss.
• Water Pump Failure: While not excessively common, water pumps are a wear item. A leak from the weep hole or a grinding noise from the front of the engine are classic signs of failure.
• EGR Cooler Issues (6.7L Diesel): The EGR cooler can fail internally, allowing coolant to be consumed by the engine. This may present as unexplained coolant loss with no external leaks.

Keeping your F-350's cooling system properly filled with the correct type of coolant is one of the most important things you can do to ensure a long service life. If you notice leaks, overheating, or are due for a flush, find a trusted shop on Repairius.