Andrew R Stewart 

There's really a shade of grey WRT when a lube is considered an oil VS a grease as greases and oils vary in their thickness. A thinner grease might be more injectable but it generally will then be more easily washed out over time with use.

The viscosity of grease, or oil, is but one characteristic that matters. The chemistry and/or additives are also quite important, especially with an enclosed part that is costly to take apart and service. An example of this is that some people have used automatic transmission fluid for IGH lubing. I've read (likely here in BF) of removing the guts and soaking them in ATF for both a "cleaning" and the after service lubing. ATF is pretty thick and has all kinds of additives compared to oils.

I'm no IGH expert (even though I rebuilt my first SA AW back when most here were not yet born) and others here might offer more opinion and experience than I have. There is a lot of posts and vids on line in various forums and video service sites that cover this stuff if you wish to dive deep. Andy