EO should be used sparingly as everyone here mentioned. I use it in most of my preperations @ 25% because I like shooting my gear through 27g pins. EO with GSO lets me do this... With that being said, I do not react that adversely to it, so I can get away with it.
Most people like to pretend they need gear dosed at 500mg/ml, so they use EO as a carrier. I am one 500mg/wk of Test and 300mg/wk of Deca, making phenomenal gains and only pinning myself once a week