In researching the archives for how to clean oil from aluminum pans, I
found the advice mainly consisted of "elbow grease". However, I found
that a spray-on product called "Lift Off" to be highly effective in
removing oil residue; after spraying, it wiped off with a paper
towel. The active ingredient appears to be "Xylol", and is mainly
marketed towards removing stickers and such. My own can is over 10
years old, so I don't know if the brand is still made any more, but
surely some other similar spray uses the same chemical. (WD-40 is not
effective.)