Ford Mercury Villager 1997 Owner's Manual page 287

If the fluid is low, carefully clean and remove the filler cap from
the reservoir. Fill the reservoir to the MAX line with Ford
High Performance DOT 3 Brake Fluid C6AZ-19542-AB or DOT 3
equivalent fluid meeting Ford specification ESA-M6C25-A.
If you use a brake fluid that is not DOT 3, you will cause
permanent damage to your brakes.
Do not fill the reservoir above the MAX line.
If you find that the fluid level is excessively low — below the
seam or ridge on the outside of the plastic reservoir — have the
brake system inspected.
Do not let the reservoir for the master cylinder run dry.
This may cause the brakes to fail.
Brake fluid master cylinder reservoir
Maintenance and Care
WARNING
WARNING
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