Engine? Motor? In the company of like-minded enthusiasts such as ourselves,casual vocabulary or subject specific slang, between members and friends is a way of building relationships between individuals, and also excludes outsiders who cannot join as they don`t speak the lingo.. As long as everyone knows what the term represents,there is no reason to get upset. On the other, very serious hand, the importance of accurate description and proper use of terminology, say when explaining a potentially dangerous task or procedure to somebody, is critical or even more depending on the situation at hand. And the more that we allow our language to become inaccurate the worse our problem becomes.. Imagine trying to tell another how to diffuse a bomb,or do an emergency lifesaving bit of first aid,with very poor communication due to serious degradation of vocabulary by one or all off the parties involved? Some words, such as "mixture" and for example, "solution" seem to be the same thing,but represented by two different words. Know the difference? Its not ones liquid and one is not as you may think. A mixture is a combination of two or more separate things thatcan be simply manually separated again. For example a cup of sugar and one of salt,mixed together. A bitch, but separable with no "Procedure" or "process" required. A "solution" is a combination of ingredients that require a bit more than picking apart. But my point is Motor,engine in a casual setting amoung friends is just casual slang part of bonding. But if you are trelling a guy over the phone how to top a car battery up , he better know that pouring water into battery acid is gonna be way different than pouring battery acid into water.