5 W 30 ( according to the 1998 Ford Ranger owners manual for the 2.5 L / 3.0 L and 4.0 L engines )
10w30
We use Pennzoil 10W30
10w30 is a good viscosity for your truck.
summer: 10W30 winter: 5W30
That would depend on what year of Ford Ranger and what size of engine it has
I would use 10W30 in the engine
Use the oil of your choice. 5w30 for colder climates, and 10w30 for warmer weather.
I use 10w30 in my 99 Ford Contour and I have no problems manufacture recommends 10w15 though. but I see that 10w15 burns too fast and that's why I use 10w30
Use 4 quarts full synthetic 10w30.
You can use either 10W30 or 5W30 motor oil or if you wish you can put synthetic oils in it too using the same grades 10w30 or 5w30
SAE 10W30 any major brand.