My OBM uses a marine grade synthetic. It holds up well to the mud and goo when we get into it.
I don't think you should worry about getting all of the Mobil 1 out of the joints, eventually it will be displaced by the new product as you continue to "fill 'er up"
06 Rubi with some sort of double ended, chrome knobbed, cross threaded, infinitely adjustable, frequently breakable, worn out flammywhammers zip tied onto it.
It used to be a jeep thing... til that sh!t broke!