The cheapest and easiest way to farm oil is to collect junk items that contain it, wait until those items respawn, and collect them again. And the absolute best places to find a large amount of items that contain oil are the following spots:
Farming Oil From Junk Items
It’s easy to find a lot of oil in the Wasteland if you know what to look for. These are the items that can be scrapped into oil: You will find a lot of these items randomly placed around, in the Commonwealth, and also as loot from enemies. But if you just want to focus on the best locations mentioned previously, then here’s their location on the map: Tip: When farming any junk items, keep in mind that most items in Fallout 4 take around 7 days to respawn. There’s a trick to knowing if the items you find contain the materials you are looking for: With TAG FOR SEARCH activated on the materials you need, the junk items that contain those materials will display a small magnifying glass when you hover them. Once you have the items you were looking for, you need to transform them into oil. To do this:
Buying Oil From NPCs
The greatest advantage of buying oil from an NPC is that you don’t need to carry any extra weight. Shipments of Oil are weightless and can be converted into 25 oil in a workshop. Buying from an NPC is also fast and easy, but very expensive. If you are still starting out and don’t have a great amount of bottle caps, this might not be an option for you. You can alternatively buy junk items that contain oil, and scrap them in your workshop. This is a list of all the NPCs that sell Shipments of Oil, and where to find them: *If you don’t have access to The Prydwen yet, continue following the main story quest to unlock it. Here’s their locations on the map of the Commonwealth:
Alternative: Making Your Own Oil
You can make your own oil by crafting Cutting Fluid from the Chemistry Station and scrapping it. Each Cutting Fluid will yield 3 oil. But to craft this item you will need four components:
Acid Bone Purified Water Steel
Here’s how to find the components you need: