Leupold has claimed to conduct extensive testing over the decades and reports neither advantage nor disadvatage to using thread locker vs oil, provided it is the low strength blue type. But, they do find disadvantage to running scope ring and mount screws completely dry.
If you degrease the holes just before you put the screws in, there is generally still solvent left in them
I've mounted literally hundreds of scopes that way, and haven't had any problems.
Locktite on guns really isn't needed if you get the screws tight in the first place
