Red Rocket is a franchise of filling stations for pre- Great War automobiles. Derelict stations can be found across the Capital Wasteland and the Commonwealth, usually in close proximity to former auto-maintenance garages, public rest areas, and suburban settlements.
Although Red Rocket was known to distribute petroleum-based fuels such as gasoline and diesel,
by  2077 certain locations in the Boston area exclusively offered reactor coolant for nuclear-powered vehicles. "Class A Coolant" was sold for the going rate of $103.99 per gallon, and "Class C Coolant" for $113.99. 
Capital Wasteland Edit
Sanctuary Hills - East of Sanctuary Hills, across a bridge.
A station in an unspecified rural area.
At the base of a fueling station, where the gas pumps would be on an ordinary station, a dirty sign is visible that appears to say "Petroleum spirit. Highly flammable."
Red Rocket refueling stations seem to appear next to almost every mechanic's workshop in the Capital Wasteland.
The Children of Atom in Megaton has a 'Red Rocket' rocket on top of their church, either taken from one of the refueling stations or taken from the Springvale Elementary playground.
There are usually one or two trash bins and/or Nuka-Cola vending machines to be found in the vicinity.
The station's apparatus is a prime example of Raygun Gothic architecture.
Mini Red Rockets can be seen at playgrounds.
After The Waters of Life quest several Enclave scouting parties will set up shop near Red Rocket stations.
Red Rocket will be a company in Fallout 4; the Sole Survivor's dog companion is first encountered at one of their stations, and a board sign is seen in the .
Fallout 4 teaser trailer
Fallout 4 - Red Rocket billboard ↑
Fallout 4 - Red Rocket, "Last Coolant Recharge" sign ↑
YouTube: Fallout 4 -- E3 Showcase World Premiere (Red Rocket price sign at 13:32)