Let's be real here, nothing locks better than cross-threading the nut.
I read a discussion by a guy who had worked in restoration of WWII aircraft, and he was commenting on the difference between the Spitfire and American planes. According to him, he said that in American planes, there were castle nuts, cotter pins, and safety wire all over the place, whereas in the Spitfire, a common expedient in the field was to use regular nuts then mash the exposed threads.
Then put it on the bottom of a toyota and drive it around in a canadian winter, it'll never come off. Ever.