I've been doing that for years when Sharon Schamber revealed she did all her thread even poly this way. What I do is have a shallow plastic bowl, pour mineral oil in it then put in the spool or cone of thread and let soak for awhile, turning it once or twice. Take it out and let drain on paper towels. It is not oily or messy when soaked in. if you don't want to soak the spool use mineral oil drops on the spool as needed.