Rust preventative for hand tools

Living in the tropics means an on-going struggle with rust on tools.



I have just dipped a handful of screwdriver bits, nail punches and drill bits in Evaporust, and about to clean the black carbon residue off them.



Can anyone suggest a coating or something that I can put on these bits and pieces to prevent further rusting?



The instructions on the Evaporust container suggest that another coat of it is good for rust prevention, but I found this to be very short term.