Bullshot grease is a high end bicycle lube, the only place I've seen it lately is from the UK online. Phil Wood makes a bicycle grease that's real close, if not a little better. From the bicycle world, there's a few similar products that would work in a fishing reel, Tri-Flow and SuperLube make a clear PTFE synthetic grease, that is clear and pretty light, neither will separate or stain. All of these are a bit on the heavy side and would need to be used very sparingly. The Phil Wood Grease and Bullshot are the most expensive, Tri-Flow is about $8 for a 3 oz. tube, and SuperLube is about $4. I've seen SuperLube in K-mart at times in the fishing section, but only in very small tubes. Both SuperLube and Tri-Flow make a light oil as well which comes in both an aerosol and in bulk liquid. (great for freeing seized or coroded parts, like stuck metal ferules on old rods).
My favorite as far as low resistance, is Lubriplate Fishing Reel Lube by Fisk Brothers, but this is not a synthetic and could separate and harden over time. Lubriplate is a bright white grease and very thin.
Here's a web link to a seller for Bullshot:
http://www.mdt-products.com/products/18 ... lshot.html
Any bike shop should have access to either Tri-Flow, Phil Wood or Bullshot grease. Be carefull though, there is a Bullshot grease that is made for tractor trailer service, it's also waterproof, but it's very thick and sticky, it's meant for lubrication the fifth wheel plate.
I used to have some older grease that was labeled "Non-Fluid Oil" which was a very, very light amber colored petroleum grease, it looked alot like the old greases you find in some vintage reels. The supply I had is gone, but the maker had been out of business for 30+ years. It came in an orange metal can, which looked like a can of car polish. I had gotten a case of it from a shop that I bought out a number of years ago.
Performance Bicycle lists most of the available bike lubes including the Phil Wood Grease:
http://www.performancebike.com/shop/search_results.cfm Too give you an idea of viscosity, the Tri-Flow and Super lube greases are about the consitency of mayonaise, the Phil Wood Grease is a bit thinner, as is Bullshot. All are quite waterproof, and will not separate or harden.
There are several bicycle greases out there that may be suited for use in a fishing reel, here's another link,
http://www.nashbar.com/results.cfm
I have been told that the Shimano grease is also a good all weather light weight grease. Just about any synthetic grease will stay consistant at all temperatures, as well as be very water resistant. The key to a fishing reel is not to over grease or use anything too heavy that will add any cranking resistance. I use a combination of both grease and several weights of oil on my every day reels, depending on where they are fished, and which type of reel. For instance, a Penn 9/0 can tolerate a much thicker grease than say a Penn 209 Levelwind, while a spinning reel is the most sensitive, and always needs a very light grease. (In many of the new reels, with instant anti-reverse, the roller bearing can only have a slight drop of very light synthetic lube, any thing heavier and it will stick, and not work when needed).