Is it more reliable to have the checkup done by computer (casa) than manually?

[jick.cejoco]

There are two kinds of liquid/fluid leaks:
Pressure leak-happens when the engine is running or the fluid is under pressure, and
Gravitational leak- originates from a higher location where the vessel or container is unable to hold liquid.
Have the engine steam washed and if available to you, use a flourescent dye with the oil in question. Usually, the leaks start to show using a black light (U.V.) by scanning the area of the leak. The source of the leak will glow like the Dickens.

If the leak is sprayed within the plane of rotation of pulleys or rotating parts ( thrown around by centrifugal force), it will always leave a tell-tale sign or trace of the leak.