Parts for your 2018 Ford Fiesta-Coolant

2018 Ford Fiesta coolant — what it does and how to look after it

Coolant is absolutely used and required on the 2018 Ford Fiesta. Ford’s own owner literature and service data specify an OAT (Organic Acid Technology) engine coolant meeting Ford spec WSS‑M97B44‑D (Motorcraft Orange) for this model year, with some later service fills moving to a compatible Ford Yellow meeting WSS‑M97B57‑A1. These specs are documented in the 2018 Ford Fiesta Owner’s Manual and Motorcraft service publications.

On a 2018 Fiesta, coolant isn’t just coloured liquid under the bonnet — it’s the lifeblood of the engine’s temperature control. It carries heat away from the block and turbo (on EcoBoost models), helps prevent corrosion inside the alloy components, raises the boiling point, lowers the freezing point, and lubricates the water pump. Without the right coolant, engines overheat, alloy passages corrode, and heater cores sludge up — none of which is fun or cheap to fix.

From new, most 2018 Fiestas were filled with Motorcraft Orange OAT coolant. Ford guidance commonly sets a long first service life (up to 10 years or 200,000 km), then shorter intervals thereafter (around 5 years or 100,000 km). Real‑world use in Australia and New Zealand — lots of stop‑start, hot summers, coastal air — can age coolant faster. If service history is patchy or the car’s done a few hard years, a preventive change earlier is smart. Always confirm the correct spec in the owner’s manual or the under‑bonnet label.

When servicing a Fiesta’s cooling system, the aim is clean, correct‑spec coolant at the right mix, with no air trapped. Many Motorcraft coolants are supplied premixed 50/50, if using concentrate, blend with demineralised water only. Never mix coolant types or colours, if the car was later serviced with Ford Yellow, stick with the same spec. Topping up with plain water is for emergencies only and should be corrected with a proper flush and refill.

Handy checks between services:

• Look at the expansion tank cold — level between MIN and MAX, no oil sheen, no rusty sludge.
• Inspect hoses and clamps for seepage, swelling, or chalky residue.
• If you smell sweet coolant or see steam, stop and investigate — don’t keep driving hot.
• Never open the cap when hot, wait till it’s cool, then bleed air as per Ford procedure after any drain.

Done right, fresh, correct coolant keeps a 2018 Fiesta running cool, efficient, and happy for the long haul.

Popular questions about 2018 Ford Fiesta coolant

What coolant type does a 2018 Ford Fiesta use?
Ford specifies an OAT coolant meeting WSS‑M97B44‑D (Motorcraft Orange) for 2018 builds. Some vehicles serviced later may use the newer Ford Yellow meeting WSS‑M97B57‑A1. Match what’s in the car and don’t mix types, check the owner’s manual and reservoir label.

How often should the coolant be changed?
Ford literature commonly states up to 10 years/200,000 km initially, then about every 5 years/100,000 km. In hotter or harsher Australian and New Zealand conditions, many workshops opt for earlier preventive changes, especially if history is unknown.

Can different coolant colours be mixed?
No. Mixing OAT types or colours can weaken corrosion protection and form deposits. If unsure what’s in the system, have it tested or fully flushed and refilled with the correct Ford‑approved coolant.