When it comes to metal on metal contact, I recommend grease most of the time, unless the manufacturer says otherwise. It is rare I will use a threadlocking compound unless it calls for it is already on the bolt or the bolt has a history of coming loose. Bolts that are properly greased or anti seized and torqued don't usually come loose maybe if it is a really cheap bolt on some rough terrain but usually they aren't coming loose when properly installed but if it does then I employ some mild threadlocker usually a blue color.