And why we are arguing then? Seems we are both in agreement. However: Unfortunately, in your above case, I would say the driver. You see, the car has a knock sensor. It would detect the engine knock caused by the too low octane gas, and would try to retard the timing to compensate. It can only retard it so far. At that point if it were still knocking, the check engine light would come on. The prudent thing to do would be to immediately stop driving the car, shut it off, and have it towed to a service center. They could read the codes stored in the computer and would be able to tell there is a fuel problem. The motor would not blow in the few seconds or so that it would take for the above scenario to play out. Now if you ignored the check engine light, and continued to drive the vehicle until the engine blew (because of the stresses put on the internal parts from putting a load on the knocking engine)........ In any event, the couple of dollars that a hydrometer costs seems insignificant in comparison to what the livestock costs. Everybody who has a saltwater tank should have (at the minimum) a hydrometer, or better yet, a refractometer. Now the not returning phone calls. That needs to be taken care of by corporate/owners. That's not good for all involved.