The Ultimate Payday 2 Big Oil Engine Guide: How to Always Identify the Correct Engine
Successfully completing the Big Oil heist in Payday 2 hinges entirely on one critical task: identifying the correct engine out of ten possible ones to steal for The Dentist. This guide provides a complete, step-by-step system for reliably finding the right engine every single time, whether you are playing on normal difficulty or the infamous Death Sentence. The process is methodical and, once understood, removes all guesswork from this notoriously confusing heist. You will learn how to read the clues provided in the game world, cross-reference them with the engine components, and execute the heist with confidence.
Understanding the Big Oil Heist Objective
Big Oil is a two-day heist. On day one, your crew steals various precursor chemicals from a Harvest & Trustee bank. On the second day, the primary objective takes place at a secluded mountain mansion housing a secret laboratory. Your goal is to locate and secure a prototype fusion engine built by a scientist named Eisenberg. The complication is that there are ten different engines scattered in the garage and lab areas, but only one has the correct combination of components needed for The Dentist. Your job is to find clues within the scientist's computer and notes to identify which engine is the correct one. Planting the correct engine in the helicopter extraction zone is the key to finishing the heist.
The Three Critical Engine Components
Every engine in the mansion is defined by three visible, interactable components. You must find clues for each of these three parts to pinpoint the exact engine number (1 through 10). The components are:
- The Engine Color. This is simply the base color of the engine block sitting on the cart. The possible colors are Blue or Orange. This is the easiest clue to find and verify.
- The Engine Cylinder Count. This refers to the number of large, cylindrical tanks attached to the top rear of the engine. The options are 4 Cylinders or 6 Cylinders. You must count these by looking at the engine model.
- The Engine Fuel Type. This is determined by the color of the large, spherical tank attached to the side of the engine. A Yellow tank indicates Hydrogen fuel. A Green or sometimes blue-green tank indicates Deuterium fuel. Pay close attention to this color distinction.
Your mission is to gather three specific pieces of intel that tell you the required attribute for each of these three components.
Step-by-Step Guide to Finding the Clues
The necessary clues are found in two locations within the lab area of the mansion: the computer in the main server room and a notepad on a desk, usually in the smaller office or lab room adjacent to the server room.
1. Find the Computer and Get the First Two Clues.
The computer is always located in the central server room, which is a key room you must access. You will need to locate either a keycard (from a guard or scientist) or a thermal drill to open its door. Once inside, interact with the computer terminal. You will be presented with two lines of text that are your first vital clues.
- The First Line (Fuel Type): This line will read either "H2" or "D2". H2 stands for Hydrogen, meaning you need the engine with the yellow fuel tank. D2 stands for Deuterium, meaning you need the engine with the green/blue-green fuel tank.
- The Second Line (Cylinder Count): This line will contain a chemical pressure formula. The only thing you need to look at is the number that appears directly after the letters "psi" (pounds per square inch). This number will be either 4000 or 6000. If the number is 4000, you need the 4-cylinder engine. If the number is 6000, you need the 6-cylinder engine. Ignore all other numbers and text in this line.
2. Find the Notepad for the Final Clue.
The notepad is usually on a desk in a smaller room near the server room or the lab bedroom. It is a physical item you must pick up. On the notepad, you will see a hand-drawn diagram of an engine. The engine in the diagram will be colored either Blue or Orange. This is your third and final clue: the required engine color.
You now have all three data points. For example, your clues might be: D2 (Green Tank), 6000 psi (6 Cylinders), Orange Diagram (Orange Engine).
Locating and Identifying the Correct Engine
With your three clues in hand, you must now search the engine spawn locations. Engines are found in the garage (first floor) and in the lab area (basement). You must approach each engine and examine its three components.
Systematic Verification Process:
- First, check the fuel tank color against your computer's first clue (H2=Yellow, D2=Green).
- Second, count the cylinders on the top rear (4 or 6) against your computer's second clue (4000 or 6000 psi).
- Third, confirm the base color of the engine block (Blue or Orange) against your notepad diagram.
Only one engine on the map will perfectly match all three criteria. Once you find it, you must interact with it to attach a parachute. This is a crucial step—simply identifying it is not enough. The engine will now be marked with a yellow parachute icon. Your final task is to move this engine to the helicopter drop zone on the mansion's helipad. This requires carrying the heavy engine, which slows movement significantly, so plan your route and use team cover.
Practical Strategies for Success
Scouting and Preparation: As soon as you enter the lab area, focus on securing the server room and finding the notepad. Do this quietly in stealth, or hold the area firmly in a loud approach. Knowing the clues early allows the team to identify the engine while managing the ongoing assault.
Stealth vs. Loud Approaches: In stealth, you can take your time to find clues and identify the engine without pressure. Use silenced weapons and control guards/civilians. In a loud approach, the heist becomes a prolonged battle. Securing the lab area and using the correct equipment is vital. The Improved Combined Tactical Vest or a suit with mobility can be good choices depending on your role.
Team Roles and Communication: Designate one player as the "Intel" specialist to hack the computer and grab the notepad. Others can start scouting engine spawns. Clearly call out the three clues to the entire team: "We need Orange, 6 Cylinder, Green Tank." This allows everyone to search efficiently.
Engine Movement Tactics: Moving the engine is dangerous. Use cover, deployable shields, and teammate support. One effective tactic is to move the engine in short, covered sprints while your team suppresses the enemy. You can also "pass" the engine by dropping it for a teammate to pick up, which can be faster than a single person moving the entire distance alone.
Essential Equipment and Skills: Equipment bags are limited. Prioritize Doctor Bags or Ammo Bags for survivability. The ICTV provides crucial protection during the engine move. Skills that enhance movement speed while carrying bags (like Transporter and Shock and Awe) are incredibly valuable. Inspire is, as always, a team-saving skill.
Common Mistakes and How to Avoid Them
Misreading the Pressure Clue: The most common error is misidentifying the cylinder count. Remember, look only for the number following "psi". It will always be 4000 or 6000. Ignore any other numbers like 689 or 15.
Confusing Fuel Tank Colors: Deuterium tanks are a distinct green or turquoise. In some lighting, they might look bluer. Hydrogen is a bright, canary yellow. If unsure, compare it to another engine's tank.
Forgetting to Attach the Parachute: You must interact with the correct engine to attach the parachute before it can be moved. The engine will have a unique model with a packed parachute on top.
Rushing the Identification: Under fire, it's easy to make a hasty check. Always verify all three components methodically. Picking the wrong engine and moving it wastes immense time and effort.
Neglecting the Server/Drill: If the police assault begins, they will attempt to destroy the evidence by disabling the server in the server room. If you haven't gotten the computer clues yet, you must defend the server or restart the hack. Alternatively, you can use a thermal drill to bypass the server hack entirely, which can be a safer but louder option.
By following this structured guide—collecting the three definitive clues from the computer and notepad, then meticulously checking each engine's color, cylinder count, and fuel tank—you will eliminate the mystery from Big Oil. This heist transforms from a confusing puzzle into a straightforward objective of intel gathering and execution. Master this process, and you will secure that prototype engine with professional efficiency every time.