If you spend enough time blending gasoline with waste oils, and give that blend enough time for settling to take place, and give yourself a way to easily remove the sediments, and inspect them, then you will find water, whether it has salt in it or not, will readily settle out within hours to days from water contaminated waste oils.
But, thanks, Tplane37, that was a really interesting factoid about using pig's blood and sea water as a fire extinguisher, which I did not know about. I am an archaeologist by trade, so I am part of how the archaeological record gets interpreted, and I can imagine an archaeologist, who did not know about this fire fight practice would interpret the presents of an abundance of pig's blood on an excavated burned wreck might interpret it as a boat hauling pigs.
Another related factoid is the reason why American barns are red, or used to be, is because, before paint companies, farmers made their own paint by blending cow blood with cow milk, which makes a polymer-like substance that protects wood, so it was painted on to barns to protect them during the US colonial period.