The recommended petrol for Ford Escape 2017 Titanium is minimum Octane 95. However, the previous user has used Octane 91- mileage still less than 2000 km.
Can I now change over to Octane 95 while there is still some Octane 91 left in the tank?
Yes, you can add 95 octane to the tank that has 91 octane in it.
Blending fuel together is harmless. Mid-grade gasoline is typically a blend of lower and higher octane from their respective tanks and mixed at the pump.