How do I compare locally made, imported and used oil machines?

Detailed Engineering Analysis

Use the same seed batch for trials and compare filtered oil, throughput and energy per batch. For a used machine, inspect screw and barrel wear, bearings, motor, controls and repair history with a competent technician. For an imported unit, check landed cost, electrical compatibility and replacement-parts lead time. For a locally supplied unit, check the written warranty and support arrangements. Ask each seller to list everything included in the quoted price.