What part(s) of the engine does this really test? It only tests how well the valves are sealing and the compression of the..compression rings right? So in the case of oil consumption, it doesn't say anything about the oil control rings, valve seals, guides, etc- yes/no?

 

In my experience, no, a compression and/or leak down test will not tell you the condition of the oil control rings.

 

A compression test certainly says nothing about valve seals at all.

 

its simply testing a cylinders ability to hold compression. that is.....rings and valves.

 

Yeah and I had bad oil rings and was eating a ton of oil and still had great compression.