Using an impact socket with your socket wrench will make your life much easier with disassembling old machines with tight nuts. You can use the high malleability of your socket wrench (its ability to turn both ways) and the strength of the impact socket at the same time.
Step 1 - Size up the impact socket
Find the right impact socket according to the nut you want to use it on. The best way to do this is to find the design (hexagonal, octagonal etc) that matches the nut best by trying it on.
Step 2 - Fit it in
Slide in the impact socket in the hole until it gets attached to the socket wrench (ends with a ‘click’ sound).
Step 3 - Use the socket wrench
By placing the impact socket on the nut and rotating the socket wrench (just twist the button on the side of the wrench if you run out of place to rotate) you will be able to loosen up the tightest of screws without worrying about the socket breaking.
Usually, impact sockets are used with impact wrenches which use their air mechanisms to create a huge amount of force that the impact socket can absorb without exploding. However, their use with normal socket wrenches works for avoiding breaking the sockets in tough conditions.