Which factor does NOT contribute to water entering oil tanks?

New oil delivery does not contribute to water entering oil tanks because when oil is delivered, it is typically transported and stored in a manner that minimizes exposure to the elements. Delivery companies ensure that the new oil is clean and free from contaminants, which includes moisture.

In contrast, condensation occurs when warm air inside the tank cools and moisture is released, leading to water accumulation. Pumping old oil into a new tank can also introduce water if the old oil has been sitting for a while and is stratified with water at the bottom. Similarly, loose vent or fill fittings can allow rainwater or humidity to enter the system, increasing the likelihood of water contamination. Therefore, new oil delivery is carefully managed to prevent the inclusion of water, making it the correct answer in this scenario.