This is a topic that is always bubbling away not far from the surface, hi. When Don says not to use 3-in-1 oil I assume he is talking about the kind in the red-white-black can. It is indeed too light for Teletype use. However the 3-in-1 brand also has a 20 wt oil in a blue and white can and that seems to be quite usable. jhhaynes at earthlink dot net