Nah not what you think. I have an oil pressure guage that has lost some of its fluid (oil of some sort I am guessing)

Does anyone know what they use inside the guage?

Have been told tool oil and also glycerine?

you hit the nail on the head man in chaps  with number two you get it from a chemist

Perthhog you never cease to amaze me with your knowledge, thanks again mate!