Originally Posted by JCL

Particularly since it is such a useless mnemonic. It is usually applied to a wrench handle. It only makes sense if the wrench handle is at 12 oclock (left = looser). If the wrench is at 6 oclock, it is opposite. If the wrench is at 3 oclock or 9 oclock, it is irrelevant. And, all of the above only works if you are looking at the end of the thread that the nut will come off. If you are taking the nut off the back of the bolt, it is all reversed yet again.

Instead, use the right hand rule. Hold up your right hand. Point your right thumb in the direction you want the nut or bolt to go. Curl your fingers. Turn the wrench in the direction you have just curled your fingers. Added bonus: you can figure out vectors and electromagnetic fields with the same right hand rule.