Your 1991 Ford Explorer 4.0 liter takes 5 quarts ( 4.7 liters ) of motor oil WITH FILTER CHANGE
In your owners manual , page 302 , comment # 5 shows that it is NOT MANDATORY to use synthetic or synthetic blend motor oil in your engine as long as the motor oil meets Ford specifications and the API " certified for gasoline engines "
For the 4.0 liter V6 engine ( 5W-30 ) For the 4.6 liter V8 engine ( 5W-20 ) According to the 2004 Ford Explorer Owner Guide
For the 4.0 liter V6 , 5W-30 For the 4.6 liter V8 , 5W-20
5W-30 is the preferred oil ( according to the Owner Guide )
10w30
5 W - 30 in the 4.0 liter V6 engine
5W30 oil is factory, Gastrol GTX is a real good oil to use.
Yes, 20 W 50 motor oil can be used in a 2001 Chevrolet Silverado with a 5.3 liter engine. This oil is great for older model vehicles.
10w30 ======================================================== According to the 2005 Ford Explorer Owner Guide : For the 4.0 liter V6 engine ( 5W-30 ) For the 4.6 liter V8 engine ( 5W-20 )
Ford uses the Motorcraft blended oil (part synthetic).
It is recommended to use 10W-30 motor oil in a Ford focus 1.4 liter engine. Desert climates are recommended to use a 10 W40 the motor oil.
I have always used Castrol Motor Oil in all my Vehicles. 10W30 or 10W40 ( the Owner Guide shows 5W-30 is the preferred oil , that's what I have used in my 1995 Ford Explorer XLT for 15 years )