2016 Ram 3500 — Coolant Capacity & Type

The 2016 Ram 3500 holds about 16.0 quarts (15.1 liters) of coolant with the 6.4L Hemi gas V8 and roughly 24–26 quarts (22.7–24.6 liters) with the 6.7L Cummins diesel, depending on cooling package and options.

Quick answer

• Total cooling system capacity (approx.):
  • 6.4L Hemi V8: ~16.0 qt (15.1 L)
  • 6.7L Cummins I-6: ~24–26 qt (22.7–24.6 L)
• OEM coolant spec: Mopar 10-Year/150,000-Mile OAT Antifreeze/Coolant, purple, meeting FCA MS-12106 (OAT chemistry)
• Mix ratio: 50/50 with distilled water (or use Mopar pre-mix). Do not exceed ~60% antifreeze for extreme cold. Do not mix with older HOAT/orange or green coolant.

Capacity by engine option

• 6.4L Hemi V8 (gas): approximately 15–16 qt (14.2–15.1 L) total system fill
• 6.7L Cummins Turbo Diesel: approximately 24–26 qt (22.7–24.6 L) total system fill

Notes:

• Actual capacity varies slightly with options (snow-plow prep, heavy-duty cooling, dual alternators/A/C, auxiliary heaters) and how completely the system is drained. If you vacuum-fill a completely dry system, you’ll get closest to the high end of the range.

Flush interval

• Normal service: Replace at 10 years or 150,000 miles (240,000 km) for the factory Mopar OAT coolant.
• Severe duty (heavy towing, high-idle/commercial, extreme temps, dusty sites): Test freeze point and pH annually after year 5 and plan replacement about every 5 years/100,000–150,000 miles, or sooner if contamination is found.

Tip: Always stay with OAT (MS-12106) coolant. Mixing in older HOAT or universal green can cause gel/sludge and heater core issues. If you’re unsure what’s in the truck, fully flush before refilling with the correct coolant.

How to refill & bleed

1. Cool and drain:
   • Let the engine cool completely. Open the surge tank cap slowly.
   • Use the radiator draincock (lower corner) and disconnect the lower hose if needed to drain more. Capture and recycle coolant properly.
2. Close and prep:
   • Close the drain. If using concentrate, premix 50/50 with distilled water in a clean container.
3. Best method — vacuum-fill:
   • These trucks (especially the 6.7L Cummins with EGR cooler) are easiest to fill using a cooling-system vacuum fill tool. Pull vacuum, verify it holds, then draw in the premixed coolant until the system is full.
4. Manual fill (if no vacuum tool):
   • Park nose-up. Slowly fill through the surge tank to the "COLD" mark.
   • Squeeze the upper radiator hose to burp air as the level drops. Refill to the mark.
5. Warm up and purge air:
   • Set cabin heat to HOT and fan on low. Start engine and hold 1,200–1,500 rpm for a few minutes as it warms. Watch for steady heat output.
   • As the thermostat opens, the level may drop; top off as needed. Avoid overfilling.
6. Cool, recheck, and final level:
   • After a full heat cycle and complete cool-down, set the surge tank between COLD MIN and COLD MAX. Inspect for leaks and recheck again after the next few drives.

Notes:

• There is typically no separate bleed screw on these applications; a vacuum fill is the recommended professional method to avoid trapped air.
• Replace the surge tank cap if it won’t hold pressure or shows coolant residue around the seal.

Common cooling system issues (2013–2018 Ram HD)

• Water pump seepage/noise (both 6.4 Hemi and 6.7 Cummins): Look for coolant at the weep hole and overheating at idle or low speeds.
• Radiator end-tank seam leaks: Plastic tanks can develop hairline cracks or seam leaks, especially on high-mileage or work-truck duty.
• Heater core restriction/poor cabin heat: Some trucks develop partial blockages; FCA published service guidance for chemical backflushing and installing updated parts in certain cases. Using the correct OAT coolant and distilled water helps prevent recurrence.
• Thermostat failures: Stuck-open (runs cool, poor heat, low MPG) or stuck-closed (overheating). Replace in pairs on dual-thermostat Cummins setups if equipped.
• Degas (surge) bottle cap pressure loss: A weak cap can cause slow coolant loss and boil-over; replace if pressure testing fails.
• Diesel-specific: EGR cooler internal leaks may consume coolant with white exhaust smoke on startup; address immediately to avoid engine damage.
• Fan clutch or fan drive issues (HD cooling packages): Overheating under load or A/C performance complaints at idle can point to a failing viscous/electronic fan drive.

If any capacity or service detail is uncertain for your exact configuration, verify with the under-hood decal and the owner’s manual or service information by VIN.

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