According to:
chemicalbook
"ETHYL OLEATE is often used as a solubilizer for lipophilic drugs, especially in the preparation of injectable oily solutions. For example, it can significantly increase the solubility and bioavailability of steroid drugs (such as testosterone and other steroid drugs) when preparing injection solutions, reducing the irritation at the injection site. In addition, due to its good tissue compatibility and low toxicity, ETHYL OLEATE can also serve as a drug carrier to help control the release rate of drugs."
So not a solvent but a carrier oil with solvent like properties. So it may prevent steroids from crashing when injected causing PIP (that's my thinking anyway).