Both the Loctite and the WD 40 are very low viscosity penetrating oils.
So how do you choose?
Viscosity is a measurement of the internal shear resistance of a fluid. It is measured in Poises. Viscosity is also related to surface tension, but is not the same thing. Surface tension is the ability of a liquid to wet a surface.
Standard lab. test results of the two products (if you can find published results), should reveal the answer.
I would guess that the spread rate of a standard droplet of a product on a standard test surface in this case, may reveal test values, or that viscosity directly has been measured.
Perhaps Choice Magazine has publshed such results. Perhaps their findings are now published on line, but I guess that you would have to be a subscriber. Pity; I don't now have access to a Choice Magazine library, I used to. If you are desperate for consumer information of any sort, the local library may subscribe to Choice Magazine.
When it is all scrubbed up, there may be very little practical difference between the two products, and it usually comes down to price and availabilty
.