How can you loosen a real tight oil drain plug?

Answer 1

The hex nut head on many oil drain plugs are very easy to damage by "rounding off" the corners due to slippage of the wrench on the nut. Do NOT attempt to use an adjustable wrench, an open end wrench, a box wrench, an improperly sized socket, or even a socket of the proper size IF IT IS WORN.

Use a tight fitting, properly sized socket with a "LONG BREAKER BAR." Be very careful to apply strong pressure on the socket to keep it up tight against the plug. This will reduce [but not necessarily prevent] the chance of it slipping off of the plug nut. Under no circumstance do you want the socket to slip off of the nut, as once that happens, the difficulty of the job multiplies by a factor of ten to one hundred, depending on the amount of damage you do to the nut.

It would help if you had a helper to concentrate on pushing the socket up tight against the nut, while you concentrate your efforts to turn the LONG breaker bar and socket.j3h.

Answer 2

use a good pair of visegrip pliers if it is rounded off clamp them on tight then as you apply pressure on the pliers handle tap the head of the plug with a hammer usually works well