Getting message"Oil Pressure Low Stop Engine". What is likely issue? on 2002 Cadillac DeVille DTS

Last time i took car in to get O2 sensor, ac blower and motor replaced ($2k) later. They also told me that I had a leak in the Oil that was going to cost $2.8K to fix...those two repairs alone are more than half of what i paid for the car.

When I add a quart of oil the message goes away has done it twice in two months

Asked by for the 2002 Cadillac DeVille DTS
The issue is the oil level is low due to the leak. If you are continually running the engine on low oil you will or may have already caused damage to the engine. Get the oil leak repaired.
Or caculate how much oil you can get for $2800.00 , and how long that would last.