I have a nice 5,3/4" columbian that had the hardest and oldest grease I have ever seen. It had tons of shavings and other matter buried in it, making a nice aggregate. It took every bit of 6 hours total of soaking and brushing with a tooth brush, steel brush, brass tube brushing, more soaking, did I mention brushing? You absoultly have to get every ounch of old gease/slag/shavings out. Honestly my opinion when you're doing most work on a post vise, oiled or greased. Slag and shavings are gonna get on the threads period. Proper periodic cleaning is the only way to get it out.