What IL is needing is the model and type number off the engine's rocker (valve) cover.
Sound like the tech didn't do his job as oil in the air cleaner has definitely a sourced problem. I had several shops here that couldn't even diagnose a blown head gasket.
There is multiple non invasive tests that can be performed looking for the problem along the most important one, the use of the experience. As IL said it can be any one of several problems.