Buy Mercedes-Benz GL450 Engine Coolant / Antifreezes

The Mercedes‑Benz GL450's radiator fluid-also called engine coolant or antifreeze-circulates through the V‑8 to pull heat away, protect against rust, and keep the SUV running near 195 °F (90 °C). Factory data and repair guides show the system holds roughly 11 to 13.7 quarts (10.5 - 13 L), depending on model year, and it must meet Mercedes‑Benz specification MB 325.0 (blue HOAT) or the newer MB 325.6 pink Si‑OAT formula. (Auto Data, Autohaus AZ, FCP Euro) A 50/50 mix with distilled water gives freeze‑up protection to -40 °F/°C. (Blauparts) Check the level monthly, flush at least every 10 years or 150,000 miles-or sooner if you see leaks or rust. (pointedthree.com) Using the wrong coolant can erode aluminum parts and clog passages, so always match the MB spec. (JustAnswer, mbwholesaleparts.com

Mercedes coolant is more than colored liquid-it carries heat, stops freeze‑ups, and fights corrosion inside the engine block and turbo chargers. The GL450's pressurized system uses a spring‑loaded reservoir cap to raise boiling point so the SUV can tow and climb without overheating. (ManualsLib)

• Capacity:
  • 2012‑2014 GL450 (4.7 L twin‑turbo V‑8) - about 11 quarts. (Auto Data)
  • 2013‑2016 models list 13.7 quarts (13 L). (Autohaus AZ)
• Approved fluid: MB 325.0 blue HOAT (pre‑2014) or MB 325.6 pink Si‑OAT (2014‑on). (FCP Euro, mbwholesaleparts.com)
• Mix ratio: 50 % coolant / 50 % distilled water for freeze and boil protection. (Blauparts)
• Change interval: Mercedes literature allows up to 15 years / 250,000 km under ideal conditions, yet many technicians advise 5 years to keep seals healthy. (pointedthree.com)

Want to see the official numbers? Check the GL450 owner's manual page 553.

1. Monthly: Glance at the translucent overflow tank when the engine is cold. The level should rest between MIN and MAX lines.
2. Every oil change: Inspect hoses for bulges or white crust that signals a slow leak. (MBWorld)
3. 5 years or 60 k miles: Pressure‑test the system; rubber O‑rings in turbo coolant lines harden over time on the M278 engine. (603 MTech Autowerks)
4. 10 years (max): Full drain, flush, and refill to prevent silicate dropout and scale. (pointedthree.com)
   A short video walk‑through of the flush is available on CarCareKiosk.

Use only fluids that carry the MB 325.x approval number printed on the jug. The Mercedes BEVO fluid list shows brands that pass factory corrosion tests. Mixing pink Si‑OAT with older blue HOAT is allowed only after a complete flush; topping off a blue system with pink without flushing can create sludge. (FCP Euro) If you're unsure, drain and start fresh.

• Rising gauge or "Coolant Low" message: Check for seepage around the water‑pump weep hole or at plastic turbo coolant tees-both common on GL450s. (RepairPal.com, MBWorld)
• Sweet smell after parking: Ethylene‑glycol odor often means a tiny leak at the heater valve under the intake manifold. (MBWorld)
• White crust near hose clamps: Dried coolant indicates a slow drip; replace the clamp and hose before a roadside failure. (RepairPal.com)
• Overheating only on hills: A sticking thermostat or air trapped after service may need a proper bleed; see this quick bleed tutorial.

1. Safety first: Engine must be cool. Wear gloves and eye protection.
2. Open the cap slowly to relieve pressure.
3. Drain: Remove the radiator petcock, then the engine block plug if accessible. Collect fluid in a clean pan.
4. Flush: Run distilled water until clear. A garden hose is fine for a gentle back‑flush.
5. Refill 50/50 mix and squeeze upper hose to purge air.
6. Bleed: Warm engine with heater on high to open the thermostat and top off as bubbles escape.
7. Verify: The dash gauge should settle just left of 100 °C mark on the German scale.

Coolant is sweet tasting but highly toxic to pets; even a spoonful can be fatal within hours. If a spill occurs, rinse thoroughly and keep animals away. (Vca) Never pour old antifreeze down the drain. The EPA recycling guide explains legal disposal at service shops or hazardous‑waste centers. Household safety groups also list antifreeze among items you should never toss in regular trash. (Better Homes & Gardens) Regular fluid checks rank high on the Car Care Council's maintenance list.

Q: What color coolant did my GL450 leave the factory with?
A: Early X164 and first‑run X166 models shipped with pale blue MB 325.0. After 2014 the factory filled most engines with pink Si‑OAT MB 325.6. (FCP Euro, mbwholesaleparts.com)

Q: Can I mix blue and pink coolant?
A: It is safe only after a full flush; mixing in the reservoir can form gel‑like sludge. (FCP Euro)

Q: How much coolant does my SUV hold?
A: Expect about 11 quarts on 2012‑2013 builds and up to 13.7 quarts on later GL450 and GLS450 trims. (Auto Data, Autohaus AZ)

Q: How often should I replace it?
A: Mercedes allows up to 15 years, but many technicians suggest every 5 years for extra peace of mind. (pointedthree.com)

Q: What happens if I use generic green coolant?
A: Non‑approved fluid can eat away aluminum, clog tiny turbo passages, and void warranties-flush it out ASAP. (JustAnswer)

Q: My temperature creeps up in traffic-what part fails most?
A: A weak water pump or leaking turbo coolant pipe are frequent culprits on the M278 V‑8. (RepairPal.com, 603 MTech Autowerks)

Q: Is topping off with water OK?
A: In an emergency, distilled water works, but restore a 50/50 blend soon to keep freeze and rust protection. (Blauparts)

Q: How do I bleed air after a hose replacement?
A: Park nose‑up, run the engine with the heater on high, and loosen the bleed screw until bubbles stop (see the bleed video linked earlier). (YouTube)

Q: Are coolant leaks common?
A: Yes-aging plastic tees and O‑rings can drip around 80 k miles. Inspect the back of the engine for pink‑white stains. (MBWorld, MBWorld)

Keep these tips handy, and your GL450 will stay cool on every journey!