Many experienced mechanics don't rely solely on diagnostic scanners and ECU codes to predict or triage faults. Long before OBD-II ports and scan tools became common, experienced technicians learned to trust their senses. Today, the most experienced mechanics still use those sensory checks, alongside modern equipment, to quickly narrow down potential faults. Beyond these, simple visual inspections remain one of the most powerful diagnostic tools, allowing mechanics to spot leaks, contamination, or unusual wear that could indicate an impending major failure. While it seems more common as the basis for a workshop prank, stories continue to circulate of technicians giving oil a little taste as part of a diagnosis.