A preconditioning fluid is provided for producing crude oil from a subterranean formation. The preconditioning fluid produces an interface with crude oil in the formation that is more elastic than the interface between formation brine and the crude oil and has a favorable Amott-Harvey wettability index for oil recovery under the dominant hydrocarbon recovery mechanisms. The more elastic interface and improved Amott-Harvey wettability index is consistent with higher recoveries of crude oil from the formation.