I just thought of this thread, Mostly because I have no clue what half of you guys are talking about. I would like your help in create a master lexicon here for everyone to use. I would like for you to list terms and there definitions (or give defs for terms posted without them) Hopefully with just a little bit of effort everyone who is new to this site can have a much better idea what is going on much more quickly. I would also like for this to be updated on a regular basis to keep it fresh. After we get a fairly large list completed we can make a new post or a guide or something and put it into an easier to read format then this post! Here are some terms I personally would love a well-thought out definition/explanation for. Oil Group'ings (I,II,III,IV etc) What are they, why are they important? PAO: Esters: Moly: Analysis (what it is, and what its used for) TBN: Shearing down: Understanding Oil weights and how they apply: Oxidation: (spell?) Blow-By: Detergents: man, were just getting started. I've been here for a while and still would like to know more about some of these things, lets make this list kick-arse!