An “oil vacuum” can be one of several things, depending on the context in which the term is brought up. In all cases, the use of this term implies the use of vacuum technology in association with petroleum products to accomplish some sort of desired function.
Several companies manufacture oil vacuums which are designed to be used to pull oil out of equipment so that it can be serviced. An example might be an oil change for a car, lawn mower, or similar piece of equipment. Using an oil vacuum ensures that as much of the old oil as possible is removed. The vacuum may have a filtration function which allows people to pull out the oil, filter it, and then return it when the service is over, or it may be designed to pump the oil into a drum for disposal.
Another type of oil vacuum is a vacuum designed for distillation of petroleum products. In this case, the vacuum is actually a very large chamber which is capable of creating a vacuum, thereby lowering pressure and reducing the boiling point. When the oil is placed in the vacuum chamber, components with a higher boiling point vaporize away, allowing for the distillation of various useful components within crude oil or partially processed oil. This type of oil vacuum is a highly specialized piece of equipment which may need to be custom designed for a specific refinery.
The third type of oil vacuum is a fictional device which is employed in a scam. The terms of the scam very, but generally speaking, people are invited to invest a company which is “developing oil vacuum technology” which will somehow revolutionize the oil industry by pulling out normally unrecoverable oil. These systems do not exist, although some oil companies have in fact developed technology which is designed to increase the amount of recoverable oil in materials like oil shale and oil sands.
The type of oil vacuum under discussion is usually clear from the context of the conversation. In the case of the first example, oil vacuums can be seen at repair shops and other facilities where equipment servicing is handled, and people who work on their own equipment may purchase lightweight models for personal use. In the second instance, oil vacuums are expensive and complex pieces of refinery equipment, while in the third case, the oil vacuum exists solely in the imagination.