I use the sqeezins from the adrenal glands of adolescent ....
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I think the secret, which of course, there isn't one, is that both Proofide and Snoseal are waxes mixed with a little oil. Not much oil, but oils suspended in wax. I personally would never use an oil that might go rancid. Not sure if olive oil goes rancid, but I wouldn't use it myself. Snoseal and Proofide are relatively cheap.