What is it worth buying a flux for smd soldering at low temperatures?

Can you comment on what flux (gel) lowering the soldering temperature is worth buying?
What is very good for smd soldering and threaded elements does not necessarily lower the soldering temperature?
I would like to ask colleagues who use some good means, which one they consider to be very good.
What do you think about this red Russian " RUSSIAN FLUX OF ALL TIMES JELLY FLUX "
- Are better? Which?
I am waiting for your opinions.

There are many good industrial fluxes, but I think quite hard to find on the market for private individuals.

Buddy daro31, could you mention a few recommendable fluxes if you are more knowledgeable about it?

Hey ... maybe try Amtech 559, admittedly it does not "lower the soldering temperature" but conducts heat well, evaporates slowly, does not thicken too quickly, it is cheap, has a gel consistency, suitable for lead-free tin (does not shoot), which makes it easier to solder . Disadvantages like any gel, like no-clean, but it would be appropriate to wash it, and it will smoke like everyone with the soldering iron (I do not recommend inhaling the fumes), no matter how much you pay for it.