what makes you think that he still has oil in his arms? If you look at his arms from when he was a younger (before he got his pro card) they looked the same. He mainly had Synthol in his delts, which have come down considerably. He may have had surgery or some type of procedure to remove the Synthol.
There is a lot of scar tissue and collagen which is permanent from all
the needles he used to stick in there. The oil itself gets absorbed pretty quickly.
Though it's pretty safe to say he will be filling them again, like Derek Anthony.
Look at the delts as well, lots of little lumps and bumps.