Cutting oil is a peculiar oil in that it supports cutting where regular oil is a lubricant. Your drill will slide on regular oil but will dig in with cutting oil. I found that a farm supply store from Oklahoma, Attwoods stocks in in the rattle can under the badge CRC which produces numerous other rattle can products. It is a foam and really does a nice job. The other thing I found that aids in good cutting is slow speeds and lots of pressure like a drill press offers. When I was younger I used to run the hand held drill at max rpms with no cutting oil and would ruin a bit every time I used one. With the above, I have bits that are over 10 yrs old and still cut like they were new. Mark