If you were lucky you'd get 10% absorption from the testicular application. But more likely much less as the oil base isn't intended to aid transdermal absorption.
In any case, injection site leakage is also a concern of mine, such that I inspect sites with a flashlight to see if I've lost anything. If the loss is substantial I will sometimes reinject. I've also gotten better about site selection, finding I have fewer problems where the skin feels looser and more pliable, such as the very upper thighs. This is for subQ. Seems like I recently read about a method that helps for IM to avoid leakage. Do a search on "Z Track Method of Injection". Basically you're pulling skin in one direction prior to injection so that upon release after injection the holes in the tissue layers no longer line up and the depot is sealed in.