What, there are no label laws/controls where you live?
I suppose it could be some sort of assembly grease. IF it is compatible with glycol brake fluid, then it is ok to use on seals and rubber parts during assembly.
But, then it wouldn't be useful for the back of the brake pads and piston, as it would most likely flow, weep, or creep out to the pads and lube them up later when temps get high.
If it IS for the back of the pads, it almost has to be silicone which you NEVER want to mix with glycol based brake fluid (not an assembly grease).
A pure silicone grease should not weep, creep, or melt at temps up to about 500F, and it is NOT simply for the purpose of anti squeal.
The silicone grease is placed there as a water barrier, as the the stock caliper system has no seal to keep water from behind the pads. A thin coat silicone grease on all metals behind the friction pad will shed water and keep it from corroding the steel and aluminum bits behind the pads. It is most important that the grease be a pure silicone, with NO petroleum compounds added to it. Silicone actually combines/mixes with nothing, petroleum compounds can be suspended within it though as bulk filler or for other lubrication purposes, that ARE NOT needed for the SOHC4 caliper design. But, petroleum will separate out of suspension with silicone with time, heat, etc. and then soak the pads with a lubricating fluid.
It's not usually a good idea to lubricate the friction pads or the rotor.
I believe if I could not easily identify an unlabeled jar of grease, I wouldn't use it, unless I tested its thermal and creep properties with a range of temperaures, or got accurate information about what it was from whoever you made the purchase.
Modern auto parts stores, and many motorcycle shops have no clue how the 1970's brake caliper design varies from modern equipment, and what it's specific needs really are. So, don't just take the salesman's word for it. They aren't really assuming any risk selling whatever they conveniently have. It's your risk.
Cheers,
