Good point by latiuss
I think its safe to inject 3 ml into quads and glutes if you give it a weeks break, 4mls in one go is a lot of oil to absorb in one shot unless you have some serious size (heavy weight bb) and I think it becomes risky developping an abcess or the gear crashing (more common with UG)
Delts and tris and bis would be max 2ml if you have size.
All in all, it just seems like a mad process that's not feasable for a guy his size.