What assumption is false regarding new incoming oil from suppliers?

The assumption that new incoming oil from suppliers is always clean is considered false because it overlooks the realities of manufacturing and transportation processes. Despite being newly produced, oil can still be contaminated during its handling, packaging, and shipping. Particulate matter, water, and other contaminants may be introduced into the oil before it reaches the end user. This highlights the importance of verifying the quality of oil before use, which typically involves testing for contaminants and ensuring that it meets the required specifications for machinery and equipment.

In contrast, the need for testing is a critical step in quality assurance and ensures that the oil meets necessary standards. Similarly, assuming oil is ready to be used without any checks could lead to operational issues if contamination is present. The reference to maintenance may relate to the ongoing need to manage and monitor oil quality in equipment, but it does not pertain directly to the immediate assumptions about incoming oil quality.