Hey bro, In most cases, I'll give my opinion, but in this case, I am going to state this as a total, 100% fact. Steroids do not have local effect. Once in the muscle, they slowly release into the blood stream and then work systemically. There is no such thing as site growth. That being said, injecting oil into a muscle will swell the tissue, and it will then expand and look fuller/feel more pumped. This is not real growth. This is an inflammatory reaction that will go away when the injections are discontinued. As you will hear many people say, if site growth was true, you would see a lot of BBers with very big asses from all the glute injections.
I would be very careful with any type of site injection. Small muscles are a lot more likely to get infected. There is far less room for the oil to disperse, than in the glute or quad. It isn't worth getting a temporary inflammatory reaction, when the outcome can be a sterile abscess.