Hi Liquid,
I think it's interesting, too, and I'm researching it, not because I find IM injections painful (which I don't), but rather because I want to determine what the best form of administration really is. There is the one individual who I quoted who said "also, subQ injections are often more painful or lead to inflammation. if you ever have accidentally gotten a steroid injection into the subq instead of the muscle you would understand," but I'm assuming he's confusing a failed IM injection with a properly done subQ injection (i.e., he probably injected into the very top layer of the muscle right at the IM/subQ interface, which I know can be painful from botched allergy shots I've done).
Since we know that testosterone is widely used in topical/transdermal applications, in which case the testosterone seemingly migrates down into the subcutaneous area, and since people don't have problems with that form of administration (except surface skin irritation due to reaction to any one of a number of components in the base gel or cream being used), then it seems we can be fairly assured that the testosterone component itself (albeit a testosterone ester) is not going to cause problems with, for example, subcutaneous fat atrophy as can happen with glucocorticosteroid (e.g., prednisone, cortisone, etc.) injections and creams. Therefore, the main issue, it seems to me, is whether the oil vehicle (i.e., the vegetable oils cottonseed and sesame seed) is likely to be a gulity culprit and cause a problem (over the long term) such as formation of subcutaneous granulomas (nodules) or fat atrophy, etc.
I see where subQ injection of non-vegetable oils such as mineral and silicone oils can cause these problems, but I can't find any examples of vegetable oils being a problem. I saw one experiment in which soybean oil was repeatedly injected/infused into animal tissue over many days in an attempt to mimic leakage from a breast implant, and there was only minimal irritation - as one might expect from such an invasive experiment.
Frank