I think the grease you have bought is similar to (or better than) the stuff that I have seen in SA 3s and 5s hubs. I've not dealt with many SA 8s hubs so I can't comment on what different kinds of grease they might have used in them, but none of the SA hubs that I have cleaned didn't clean up using the normal solvents.
In the broader scheme of things I would be surprised if they used a Silicon based grease in an IGH because it would be both expensive and a poor lubricant in most cases. I don't claim any special knowledge here but if there are any Silicon greases that are suitable for this kind of thing I'd be interested to hear about them.
The factory grease that I have seen has always resembled Castrol LM but made one or two NLGI grades thinner. Greases often smell the way they do because of the oils and soaps that are used in them. Whenever they have a significant amount of EP additives in them these tend to dominate the aroma (think how gear oil smells vs engine oil) and solid lubricants obviously change the colour.
I'd expect the new grease you have bought to smell a bit more like gear oil than (say) Castrol LM grease. As it happens I think it will work OK if applied correctly but don't assume that the mention of sturmey archer on the can makes it so; this reference is in respect of SA motorcycle gearboxes etc from the 1920s. The grease is used in quantity inside these gearboxes. Note that this kind of grease thins appreciably when it is sheared or when it is hot; if it never gets hot it may never get to all parts of the hub unless it is placed there from the start.
so if you are using this kind of grease the best way to clean and relubricate this kind of hub is to dismantle it and reassemble it, applying grease to every part as it is assembled. That is pretty much how they do it in the factory.
Even removing the centre from the hub and washing the whole assembly in solvent (eg. paraffin) risks two things; first that the assembly is contaminated with solvent (which is a good way of degrading any new lubricant) and second that the new lubricant won't penetrate to the pinion bushings etc and other places where it is really needed.
Normally if greases separate it is viewed as a bad thing, but with externally applied grease of this sort on an IGH centre it might be a good thing; the separated oil might be the only thing that penetrates the least accessible parts of the hub.
If you apply about double the quantity of grease vs the amount used from new this will help the grease to get everywhere it needs to, but.... the excess will leak out and make a mess or onto/into any hub brake there might be. It also risks the hub going baulky in cold weather.
BTW the lack of mobility of the standard grease is clear enough; when I have dismantled failing SA (or shimano) hubs and parts have started to wear or break up, the shrapnel gets mixed with the grease but normally remains confined to the region where the wear is happening. It is unusual to find debris strewn throughout the hub, whereas this is exactly what happens inside an oil-lubricated hub.
SB has some useful info on the topic of lubrication here;
http://sheldonbrown.com/internal-gears.html#lubricationcheers
)
I would prefer to adopt a quicker method! Will it be OK to flush it with white spirit, do you think?
