How much oil do you use in a day?

Most vehicles use 5 quarts of oil. The change interval for those who are the most diligent is 3,000 miles.

When oil is being "used" it goes to one of 2 places. IT either gets burned, or leaks out. Burning suggests a few possible malfunctioning components such as seals, or valve guides. Improper ring-seating in the cylinder can cause burning etc..

So, IN ANSWER to your question; a car that is running properly would probably "use" about a 1/2 to full teaspoon of oil a day. This use is a combination of burning, leakage, absorption in to certain engine components. It really is a very small amount of oir, and even a 1/2 teaspoon is a lot when a vehicle engine is in proper repair.