You get Penrite in Poland ?
Given Penrite 10-Tenths is mostly PAO and some ester, it's definitely the add pack, not the base oil IMO. These threads come along regularly with all brands, sometimes its low storage temperature, sometimes it's a bit of moisture in the oil attaching to a particular add. Sometimes it's white and fluffy, sometimes it's black and small.
Me ? I would just pour it in the engine and use it, milky bits and all. The engine will quickly heat and remix the oil, driving off any moisture (if present). I've heard of people warming and shaking oil, but I just let the engine do the work for me.
Most add packs have a treatment rate such that they can last a long oil change interval, this means they start out generous, so that the oil is still OK 10k miles later after some of the add packed is depleted or used. So it's not like all the add pack needs to be instantly available, it has a reserve, so letting the engine mix some of it back in isn't a problem to me.
BTW -20C is very cold for Australia, that oil would never see those low temps here. Which viscosity grade is it ?
And Welcome !!