This should be helpful:
Structural Insights and Intermolecular Energy for Some Medium and Long-Chain Testosterone Esters
"The solutions contained mixtures of benzyl alcohol, benzyl benzoate and oil, with a volumetric ratio of 2% benzyl alcohol, 20% benzyl benzoate and 78% oil."
"MCT for medium-chain triglyceride, and GSO for grape seed oil. Unfortunately, the evaluation of the solubility of the enanthate ester was not possible because the solutions became transparent, gelatinous mixtures. Analyzing the values, it can be noted that there is no correlation between solubility and the length of the ester. The shortest ester (TCyp) showed an average solubility of roughly 255 mg/mL, the longest one (TUnd) was characterized by the lowest solubility of roughly 197 mg/mL, and a considerably greater solubility of about 2.5–3 fold greater (534 mg/mL) was recorded in the case of TDec."
View attachment 278716
it looks like testosterone decanoate can hold up to ~540mg/ml in 20% benzyl benzoate and 2% benzyl alcohol in MCT oil.