greasy moth abdomens

I just received this O. goliath from a seller. The hind wing are semi-tranasparent compared to the forewings, and the envelope has "oils" on it. I understand soaking in Toluene (which I just purchased) is an option. Two questions: 1) is it better to soak while in the dried state, or better to soak after softening...I know soaking in acetone can cause micro and macro-cracks in the wings, I guess to excessive drying, but I have never worked with Toluene before, and 2) how many soaks, and for how long should each soak be .

Thanks in advance for your time.
Michael