The only time that you add oil to a refrigerant circuit is to replace the oil lost with component removal or if you had a violent leak that spewed a lot of oil. A std leak does release a small amount of oil, that's one way that you find leaks (pro-tip), but not enough to require replacement. If you over charge with oil you may either kill the compressor or cause degraded cooling performance.

George

 

For reference to help you with your project:

George