Sheldon Brown used Phil oil in his 3 speed hubs. I use whatever is in my oil can, typically something in a 20-30wt range. I used 20wt ND(non detergent) for years because it was what I had sitting around and it was required in some other piece of equipment that I had. The key is to use oil. Heavier weights are going to make the hub sticky and in cold climates cause some problems with the internal stuff moving. These are not high speed, high temp hubs, so as along as you have some lubrication they are happy.
Aaron
