Choosing The Right Fuel; Octane Recommendations - Ford Escape 2009 Owner's Manual

Maintenance and Specifications
WARNING: The fuel system may be under pressure. If you hear
a hissing sound near the fuel filler door (Easy Fuel™ "no cap"
fuel system), do not refuel until the sound stops. Otherwise, fuel may
spray out, which could cause serious personal injury.

Choosing the right fuel

Use only UNLEADED fuel or UNLEADED fuel blended with a maximum
of 10% ethanol. Do not use fuel ethanol (E85), diesel, methanol, leaded
fuel or any other fuel. The use of leaded fuel is prohibited by law and
could damage your vehicle.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives.
Note: Use of any fuel other than those recommended may cause
powertrain damage, a loss of vehicle performance, and repairs may not
be covered under warranty.

Octane recommendations

Your vehicle is designed to use
"Regular" unleaded gasoline with a
pump (R+M)/2 octane rating of 87.
We do not recommend the use of
gasolines labeled as "Regular" in
high altitude areas that are sold with octane ratings less than 87.
Do not be concerned if your engine sometimes knocks lightly. However, if
it knocks heavily under most driving conditions while you are using fuel
with the recommended octane rating, see your authorized dealer to
prevent any engine damage.
292
87
(R+M)/2 METHOD