I want to fill up the coolant of my Renault Clio III because it's at the minimum level. I've bought a bottle of official Renault GLACEOL RX type D coolant. This new one has a greenish/yellow color but the coolant already present in the reservoir has a light yellow color. Is it OK to mix them up as I've learned you may not mix different coolant colors? Or is it possible that the coolant present is some kind of one-size-fits-all coolant (my garage is not an official dealership).