headrc,
There is one Logan 2500 Series Operator's and Parts manual and one Parts manual in Downloads. The manuals on most make machines have either a drawing and list or a list or all lubrication points on the machine, along with how often to do it and what lubricant to use. The Logan one has some of that information buried in the text, so you will have to read through the paragraphs to find it. Unfortunately, the recommendation for the headstock sump is for either of two specific makes and type numbers, either Keystone 122-7X or Standard Oil Amovis 5X. They don't give viscosity or generic type. Unfortunately, Keystone was bought by Total who pretty soon discontinued most of what Keystone made and I don't know what happened to Standard Oil. However, the conclusion of one Google search result which is in another thread in this same Forum concludes that the lubricant referred to is grease. That is obviously incorrect as the same lubricant is used on the "oiless" bushing in the driven pulley.
All that I can suggest is to pull the top cover and see what's in there in the Well, which I assume means sump.