Plenty of oil-based products are available in stores and on-line, designed specifically for the purpose of removing rust from various metals, but most consumers have oils at home that also can do the job in many instances. Once rust forms, you want to remove it as soon as possible. Left alone, rust moves deeper into the metal and spreads.
Chrome and Bare Steel
Light oils are best to remove rust from chrome. Light oils also sometimes work on bare steel. An example of a light oil is WD-40. Just spray a light coat on the rusty spot, wait approximately 10 minutes, scrub the spot with a small bit of steel wool and wipe off the oil with a clean rag.
Steel and Stainless Steel
A penetrating oil, such as linseed oil, is good for cleaning rust off steel and stainless steel items, such as hand tools. Put a thin coat of linseed oil on the rusty spot and let it sit for approximately 10 minutes. Scrub the spot with a stainless steel brush. Alternatively, use steel wool or sand paper. Once the rust is gone, wipe off the remaining oil so its does not dry and leave a gummy residue. You may choose to clean off the item with warm soapy water. If so, dry it thoroughly to prevent rust from reoccurring.
Vegetable oil works well for removing rust from cast iron, such as a cast-iron skillet or pot. Begin by pouring two to four tablespoons of salt and an equal amount of vegetable oil on the affected area, and scrub using a paper towel. Concentrate your efforts on the rusted area, but spread the mixture across the entire surface. Add more salt and vegetable oil if necessary. If the rust is stubborn, you may need to scrub with a bit of steel wool. When done, wash the skillet or pot with dish washing liquid and warm water.
The marketplace offers countless commercial products and processes for rust removal. Among these are oil-based products, petroleum-based products, rust converters, sand blasting, electrolysis, acids and alkalies. If you are interested in one these, ask questions and read available literature to make sure the product or process is right for the job.