The variation is huge. Generally free base steroids have poor solubility, esters increase it and the heavier the ester the more soluble in oil (and less in water, which is why heavy esters release more slowly, blood is a water based emulsion).
Free base steroids may crash at 100mg/ml or less, while very heavy esters like undecanoates or undecylenates may well hold a solution up to a whole gram per ml.
Then there's solvents like ethyl oleate which dramatically increase the concentrations that can be reached (for example acetates at 200mg/ml or more become possible by adding as little as 1/4 EO, while in pure vegetable oil it's not unusual to see them crash at 100mg/ml), but are normally used as a last resort because of price and because many people have adverse reactions to it.
I bet something like testosterone undecanoate in a pure ethyl oleate solution could go up to several grams per ml, but nobody's gonna produce that.
post edited by Uriel - 2014/12/24 20:48:29