Which clue does NOT indicate the presence of an abandoned buried fuel oil storage in a house with a gas fired furnace or boiler?

The presence of a deteriorated brick chimney serving the furnace with deteriorated mortar joints does not directly indicate that there is an abandoned buried fuel oil storage tank. While deterioration can suggest issues related to age, wear, or lack of maintenance related to the heating system, it does not provide specific evidence of an underground storage tank's previous presence or abandonment.

On the other hand, clues such as small diameter copper tubes emerging from the foundation and an appropriately sized vent pipe are more direct indicators associated with oil storage systems. Small diameter copper tubes can suggest connections to underground systems, while a vent pipe is typically necessary for releasing vapors from an underground tank. Additionally, knowing the neighborhood's oil heating history can provide context about the likelihood of such systems being present, which makes it relevant to the possibility of abandoned oil tanks. Thus, the deterioration of the chimney, while significant in assessing the overall condition of the heating system, does not serve as a specific clue regarding underground fuel oil storage.