Spread shelled raw peanuts in a shallow pan.
Place in a preheated oven, on middle rack, and roast for 30 to 35 minutes.
Stir occasionally during baking.
Check brownness by removing skins from a few nuts.
If you have purchased peanuts without skins, you will not have to roast them so long.
Remove from oven and cool.
Transfer roasted peanuts to an electric blender and blend about one minute.
Gradually add the oil, one tablespoon at a time, blending thoroughly.
Stop blender from time to time and push large pieces of peanuts away from sides of blender with a rubber spatula.
Add salt.
Spoon peanut butter into jar with tight fitting cover and store in refrigerator for several hours before using.
Peanut butter becomes firm upon standing for several hours.