The Nuka-Cola Challenge

 is a Fallout 3 quest connected with the Nuka-Cola soft drink. It is also an Xbox 360 and PC achievement.

To start this quest, find Sierra Petrovita at Girdershade, which is located west of Jocko's Pop and Gas Stop and SW of Smith Casey's Garage.

Upon finding Sierra Petrovita, she offers you to take the "Nuka-Cola tour," which consists of viewing the large number of Nuka-Cola collectibles she owns. If you agree to take the tour, she will show the player around her home, discuss various Nuka-Cola facts and talk about some of the items in the room. After the tour, she gives the player an Ice Cold Nuka-Cola.

She then asks the player to collect Nuka-Cola Quantums and says she will pay 40 caps for each bottle. Once she has been given 30 bottles, enough to fill her Nuka-Cola Vending Machine, she provides a schematic for the Nuka-Grenade.

After exiting her house, Ronald Laren will ask the player to instead give him the Nuka-Cola Quantums, as he hopes that giving them to Sierra will improve his chances of having sex with her. He offers to pay the same price for the Quantums, though a successful Speech check will cause him to double the payment. You also have the option if you have the Black Widow perk to do a threesome in exchange for him finding the bottles.

The name of this quest is a reference to "The Pepsi Challenge," a taste-test marketing promotion run by PepsiCo since 1975.

Information in the Nuka-Cola Plant reveals there are three caches of Quantum, in Paradise Falls, Super-Duper Mart, and Old Olney. Each location has only about 5 bottles, so you'll have to find more on your own.

Bottle locations
An external guide lists exact bottle locations. by MdsFinest

There are a total of 90 in the game, not counting those found in vending machines. There is a small, purely random chance to find Quantums in vending machines.


 * Jacko's Pop & Gas Stop. NW of Tenpenny Towers.
 * Eulogy's Pad in Paradise Falls, behind a staircase.
 * Dukov's Place. On a shelf behind the bed and another in the vending machine in upper bedroom. Needs to be stolen.
 * Hamilton's Hideaway. In a crate on a desk towards the back of the cave.
 * Super-Duper Mart. In some crates in the pharmacy there are a total of three.
 * NW of the Super Duper Mart, along the river, you'll find a destroyed bridge. Go across the bridge until it ends and jump into the water. Swim just a bit further to the next section and look around, you should spot many Nuka-Cola bottles floating around the surface, and among them, a Nuka-Cola Quantum.
 * On top of the giant cage just inside one of the exterior doors in Springvale Elementary. You must jump on top of it from the second story area to get this or shot it from the cage.
 * One is located in the Planetarium maintenance room in the Museum of Technology.
 * At least five bottles are located in the back of a truck on a road east of Old Olney, a destroyed city with an intricate sewer system that contains a set of experimental medical power armor, and a large number of Deathclaws. Old Olney is situated near Vault 92. The truck can be found next to a red rocket ship.
 * One is in the Old Olney sewers in a room with some bedding
 * There is one at Smith Casey's Garage north of Jacko's Pop & Gas Stop
 * One at the Sub-Powerstation at MDPL-13 Power Station, on the workbench as soon as you enter. There is also a schematic for the Railway Rifle.
 * One at the Sub-Powerstation at MDPL-16 Power Station.
 * One is in Dave's room at the Republic of Dave. Needs to be stolen.
 * One at Georgetown East inside La Maison Bearuregard at the upper floor on a shelf
 * One is in Dunwich Bulding, directly south of Girdershade.
 * One is at Rockbreaker's Last Gas in the fenced area, on top of a Nuka-Cola machine.
 * Takoma Industrial, far north of Rivet City and east of Chevy Chase, on the eastern-most edge of the map: Enter the door on the north side of the Factory (where the radioactive pond and the water tower are), and go up the stairs to the left. You will notice some wood planks on the other side of the railing. Jump over the railing onto the wooden planks, and then onto the small ledge down below. There is a Nuka-Cola Quantum on the other side of the generator.
 * Tenleytown/Friendship Station: Inside of the Farragut West Metro Station in the big room to the North on a bench up the stairs.
 * The Cave System of Oasis: In the room after the room with Harold's heart, there is a Mirelurk King, a Mirelurk Hunter, and a Mirelurk. The Quantum is down where the Mirelurk King is.
 * One is in the office at Greener Pastures Disposal, same location as the Agility Vault Boy Bobblehead
 * Vault-Tec Headquarters: On the second floor in the Vault-Tec Corporate Offices on a shelf on the Northern section of the map.
 * One next to the AntAgonizer's throne
 * One in the Fort Constantine CO Quarters, in the room on the right (the kitchen area).
 * To the Southeast of Fort Constantine is ruined building with a workbench, a bed, some Shishkebab schematics and a bottle on the roof. It's about halfway between the bomb storage building and the Satellite towers in the distance.
 * One in the National Guard Depot bunker, underneath the table with the Experimental MIRV.
 * One can be found in the same place as the Burnmaster, in Franklin Metro Utility.
 * L.O.B. Enterprises, at Falls Church East: As soon as you enter the L.O.B. Enterprises building, take a right and then take the hallway left. Keep going West-Northwest, and you will eventually come to a room with a set of stairs going down. Across the stairs (don't actually go down the stairs, just look across), you will see a Nuka-Cola Quantum on a shelf. (This building also contains lots of Turpentine, Tin Cans, and Abraxo Cleaner for making Nuka Grenades.)
 * One can be found in statesman hotel in the bar area.
 * During the Picking up the Trail part of the main quest, you will enter a part of Lamplight Caverns called Murder Pass. MacCreedy has to open the door for you, so talk to him first. As you make your way through Murder Pass to the objective, you will find a Nuka-Cola Quantum on a metal shelf.
 * From the Grisly Diner, go North by east and you'll find a smoking, abandoned shack with radiation. The Quantum is in the bathtub.
 * One is located in one of the trucks behind the Nuka-Cola Plant
 * There are three in the Nuka-Cola Plant packing area, you need to access the packing terminal and select Quantum with as per the memo causes the machine to jam.
 * There´s one in a locked room on the first floor of Alexandria Arms
 * One is located due North of Mason Dixon Salvage, on the corner of a metal roof near two Brotherhood outcasts, just shoot it off, shooting doesn't damage it.
 * There is also one in an Abandoned Tent North East of Mason Dixon Salvage.
 * A Scavenger with a dog and a missile launcher offers one for sale for 100 caps, 50 if you have good speech. Found him North East of the Super-Duper Mart.
 * One in an abandoned truck between Andale and Fort Independence. The truck is next to a highway support column.
 * Roosevelt Library, on the eastern-most side of Roosevelt Academy: As soon as you walk in, there's a Nuka-Cola Quantum to the left on a desk.
 * Everglow National Campground: Take the road to the East and when you get to the intersection, take a right and immediately to your left is a wrecked semi & trailer with toxic barrels. The Quantum is on the ground by the barrels.
 * Lucky's: There is one in a one in a wrecked display case, it needs to be stolen.
 * In Vault 108 entrance floor in a small storage room adjacent to the malfunctioning generator. Behind several yellow metal crates is an metal ladder, the bottle is on top of the ladder.
 * One bottle is in a vending machine under the Red Rocket sign in Springvale, on the way to Megaton.
 * One bottle is north of Agatha's House on the way to Minefield, under a power trestle with a skeleton, and BB Gun and two cans of BB's on a chair. It is immediately south of a fenced power junction with a few empty bottles.
 * One in a box under a table, next to two Nuka-Cola machines in the Museum of History Lower Halls.
 * One inside Red Racer Factory very top floor CEO offices, The Surgeon's room. Inside the small room that is lit up in red.
 * Vernon Square East inside down a dead end subway tunnel there is living quarters with a safe and Quantum on the shelf.
 * In Vault 92, in the living quarters past the male room. You can see the bottle behind the window.
 * In the Deathclaw Sanctuary, near the Endurance Bobblehead.
 * In the Yao Guai Tunnels.
 * In Fort Bannister's Commanding Officer's Quarters, on the ground in the scientifically themed area.
 * In the Lincoln Memorial Maintenance room.

Rewards
Sierra pays you for them (40 caps each). Once you give her enough to fill her Nuka-Cola Vending Machine, she gives you the Schematic for the Nuka Grenade. In the future, she will also make you a Mississippi Quantum Pie if you bring her the ingredients.

Giving the bottles to Ronald Laren results in a loss of karma (150?) and double the caps (80 caps each) if you succeed in the speech check, otherwise you get 40. Once the quest is complete (if you gave him 30), he goes next door straight away and starts making moves - only to have Sierra completely misunderstand his advances.

For maximum money, it's possible to give 29 bottles to Ronald, and 30 to Sierra. However, a total of 59 bottles is a difficult achievement and will make it very hard to make any Nuka Grenades or Mississippi Quantum Pies as Nuka-Cola Quantums are semi-rare.

Theft
If you are of the kleptomaniac type, you can steal all of Sierra's Nuka-cola. There are about 70 bottles in total, you will lose about 400 Karma doing so. She doesn't seem too depressed if her prize collection suddenly disappears (provided she doesn't catch you). If she does catch you, she tends to flee. Don't bring Dogmeat because he will attack her if she flees.

After the quest, using the "unlock" console command on the Pristine Nuka-Cola Machine will allow you to steal back your 30 Quantums.

Bugs

 * Sometimes, Sierra Petrovita will run around her home in "fleeing" mode for a random period of time. In some cases, it will be absolutely impossible to talk to her. Reloading a save will not always fix this. It appears to happen randomly, but known causes include the player killing an NPC that she likes (Ronald) or having a hostile NPC follow the player into her house. Bringing Fawkes into the house also seems to trigger this. Often there will be a random encounter outside of the house - try to kill everything before entering.


 * The quest never updates after you get the manifest from the Nuka-Cola Plant Factory Floor. The quest counts the computer terminal that is located in the same room as Milo the Shipping Foreman as the manifest. Just use the Terminal, it isn't locked.