Engine Oil Leaking problems of the 2005 Toyota Prius

This is the first car we ever owned that ate oil. We are meticulous about servicing the car as recommended every 5000 miles. At the service for 100,000 miles which we did at 99,400 miles, there was no oil on the dipstick. At 103,000 miles the alarms went off 3 times to indicate there was no oil. We put in 2 quarts and took it to the shop for a diagnostic. Googling showed many other people with the same problem - no oil leak anywhere, but no oil in the car either. Toyota apparently knows of the problem and has informed service providers but will not acknowledge this problem to the car owners. We now carry oil in the car and check every time we put in gas to make sure we also have oil. The service shop suggests a $3500+ rebuild of the engine. We can afford to check oil and add it as necessary instead of rebuilding an engine that will end up with the same issue. It is unacceptable that the expectation is to add oil between every 5000 miles, as recommended by manufacturer, instead of the assurance that the car will be able to make it to each 5000 mile interval without adding additional oil. We also cannot afford to have the engine seize up in what is marketed as a very dependable car from a very dependable manufacturer. Apparently Toyota doesn't make cars that exceed a lifetime of 100,000 miles and are also a very undependable manufacturer of cars.