My non-scientific observations.... Bits dont last as long when using oil...I used to use whatever oil "scraps" I had left over in the bottom of quarts, etc.. Oil would smoke, make a stink, and when cutting did nothing for heat...which is the #1 enemy of bits. Well I take that back....SWMBO yelling at me saying the whole house stank (my work/machine shop is in the basement) is the #1 enemy... :laughing:
When using my soap & water mix, I'm serious when I say after drilling a 3" hole in 3/8" plate, I could immedietly touch the holesaw and the teeth were room temp. Other then the paint being worn off the holesaw, you cant tell they're used.