Add all ingredients to the bowl of a mixer. On medium speed, mix until smooth with no lumps of shortening. Scrape down sides of bowl as needed.
Store at room temperature in a covered container such as an 8 ounce mason jar for 3-6 months.
Stir before using if there is a layer of oil on top. With a pastry brush, apply to bottoms and sides of pan anytime a recipe says to "grease your pan", or "grease and flour your pan". Apply liberally for any recipe that uses a lot of sugar or produces a sweet, sticky product.
Notes
Any neutral oil can be used in place of vegetable oil. I like to use vegetable oil because I always have it on hand, and it is an inexpensive choice.