The Fjordur map of Ark Survival Evolved has many oil veins where you can set oil pumps to passively collect oil for you. Installing a pump on an oil vein is very worthwhile on a server, but I probably wouldn't bother in single player, unless you find pumps in drops. The following is not a complete list of veins, but as I discover more, I will add the coordinates of these veins to the list.
Fjordur Oil Vein Coordinates
37.4 95.5 Inside cave with metal nodes