What are swivel or flex sockets good for?
Short answer: Swivel and flex sockets have a built-in universal joint that reaches fasteners at an angle, which helps in tight engine bays, but they reduce torque accuracy and can bind under heavy loads.
Flex sockets combine a socket and universal joint in one compact unit that is shorter than a socket plus a separate joint. They reach awkward fasteners on exhaust manifolds, starters, intake components and transmission bell housings where a straight drive cannot line up.
Because they bend, they can slip or bind under high torque, and they reduce the accuracy of a torque wrench reading when used at an angle. Use them to break fasteners loose and run them, then do the final torque with a straight drive where possible. Choose impact-rated flex sockets if you use them on an impact tool, since standard ones can break.
Keep the operating angle as small as possible, and inspect the joint for wear and play. A worn joint can suddenly fold, and the resulting slip is a common cause of skinned knuckles, so pull rather than push on the ratchet when you can.
Tools used for this job
General guidance only. Follow the vehicle and tool manufacturer's procedures, and confirm vehicle coverage on the tool maker's list before buying.