Well you get what you pay for, if you get a $25 oil analysis you get $25 analysis. If you pay $500 you are going to get a $500 analysis. For most people the $25 analysis works great and probably provides them with more information than they know what to do with. But the $500 analysis is going to be more accurate and more precise. Just for an example you are not going to get an FT-IR analysis at a $500 lab you are going to get GC, DSC, TGA, and titrations for TAN and TBN. You will get a difference in readings of instead of 5% +/- .2 for a soot reading with the $25 analysis you will get a 4.824% +/- .001 with the more expensive one. Now these aren?t dead on numbers here but I hope it gives you an idea. In most cases you would just round up to 5% and be happy with that. Basically you are paying for a higher quality of testing procedure.