I really wouldn't do this...first reason being if the car is hot then the screw is also hot meaning it expanded
second of all if these screws are really that tight (I don't have a oil temp fitted so wouldn't know) then putting a lot of force on a hot screw might cause it to snap inside the block...now you really don't want that or else you will have to drill it out!
I think first step is getting a proper allen tool which can actually resist some real force
and then loob it and have it 'sink' in around the screw. Then roll up your sleaves and put some sweat into it haha. even pop a can of spinach