Shopping for Mercury Oil

My family loves to go boating. Just about everyone in the family owns a boat. Every summer, we would get together and go out to one of the islands with our boats. For some reason, we almost always took hours to leave the marina. My grandpa was obsessed with keeping his boat perfectly maintained, so often he would have some last minute project to complete.

I remember one time, he sent my mother and I to get Mercury oil from the shop near the marina. Of course, he did not think to tell us what kind to get. We were left staring at various different types of oil, oblivious to whether he needed premium oil or some other type. Eventually, we were delayed even longer by having to ask him.