The correct coolant is Ford Motorcraft coolant that is premixed in a 50/50 ratio and labeled Ford-approved for the 3.5 EcoBoost engine.
For the 2018 3.5L EcoBoost, Ford designs and tests cooling systems with specific approved formulations. Use a product that is explicitly Ford-approved (Motorcraft or an equivalent that clearly meets Ford’s specifications for this engine family). This coolant is typically ethylene glycol-based and formulated to be compatible with aluminum engine components. If you’re unsure, consult the owner’s manual or contact a Ford dealer to confirm the exact specification before mixing or refilling.
Approved coolant options
Below are the commonly recommended choices for the 3.5 EcoBoost. Use the option that matches what you can source locally, ensuring it is Ford-approved or explicitly stated to meet Ford's specifications for this engine family.
- Motorcraft Premium Gold Engine Coolant, premixed 50/50 – Ford-approved and designed for Ford aluminum engines.
- Motorcraft Engine Coolant Concentrate – to be mixed with distilled water to create a 50/50 premix, used only if you follow exact Ford guidelines for ratios.
- Other coolant products that are explicitly Ford-approved and labeled to meet Ford specifications for the 3.5 EcoBoost – verify compatibility with the vehicle’s manual or dealer guidance.
When choosing an option, ensure the product is ethylene glycol-based, silicate-free, and compatible with aluminum engine components. If in doubt, stick with Motorcraft-brand coolant or ask a Ford service advisor for the exact formulation your vehicle requires.
How to handle refills, mixing, and maintenance
The following guidance helps ensure proper cooling-system performance and longevity when you service or refill the coolant.
- Make sure the engine is completely cool before opening the cooling system to avoid scalding or pressure release.
- Check the reservoir level when the engine is cold; top up with the same premixed coolant to the appropriate "Full cold" line.
- If you’re using concentrate, mix only at the recommended 50/50 ratio with distilled water, then use the mixture promptly or store according to the label’s directions.
- Inspect for leaks, worn hoses, a faulty radiator cap, or a failing water pump; replace any components as needed before refilling.
- After refilling, start the engine and allow it to reach operating temperature while you check for leaks and ensure the coolant circulates properly. Recheck the level and top off if necessary once the system stabilizes.
- Dispose of old coolant responsibly at a certified recycling facility; never pour it down drains or on the ground.
Following these steps helps maintain proper cooling performance and protects the engine from overheating, corrosion, and freezing in cold weather.
Summary
For the 2018 3.5 EcoBoost, the safest and most reliable choice is Ford Motorcraft coolant that is premixed 50/50 and Ford-approved for this engine family. If you use concentrate, mix it exactly according to Ford’s guidance. Always verify the exact specification in the owner’s manual or with a Ford dealer, especially if you’re using aftermarket products. Proper selection, mixing, and maintenance will help keep the 3.5 EcoBoost cooling system operating effectively for years to come.