The DeOxit is an excellent contact cleaner and lubricant for contacts - but not the best choice for general lubricating. As you said Derek - a good "light oil" is what's needed, but I think 3-in-1 may be too much even. Generally lubricants intended for watches / sewing machines etc would be ideal, as long as they are low residue and don't have tendencies to thicken over time. The environment of a microdrive motor is not particularly stressful heat wise or moisture wise (you would have other issues in your house if it was!), but the motor is subject to dust ingress over time, and the mechanism of the Microdrive means stops and starts.