Ford Econoline/Club Wagon E-150 Owner's Manual page 328

E-Super Duty vehicles:
4. Check the fluid level in the power steering
fluid reservoir. The fluid level should be
between the MIN and MAX lines on the side
of the reservoir.
5. If the power steering fluid is below the MIN
mark, add fluid in small amounts until the
level is between the MIN and MAX lines on
the side of the reservoir.
Power steering reservoir
If you check the power steering fluid when it is
cold, make sure that the fluid reaches the MIN
on the reservoir. The reading will only be
accurate if the fluid temperature is
approximately 50˚F to 85˚F (10˚C to 30˚C).
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