Hey man, try using some brake & parts cleaner, this is a product used in the automotive, I am a mechanic by trade, so I"ve had a chance to use this in a number of different ways, it dissolves grease or oil on contact, it is a great adhesive remover, it is also a great brush cleaner when you use oil based paints, also, it does not attack plastics.
This is a petroleum distillate product, it will produce fumes so use it in a well ventilated area. It comes in spray cans and it is marketed by many different companies, winns, wurth etc. about $4.00 a can. You should be able to find it at your local auto parts store. I like the fact that you can get so many uses out of one can, and so many different applications, I call it the "Universal Stain Remover". of course as long as we are talking "Oil Based".
What I do if the job is small, I spray some in a cup and work the stuff with a brush, or spray it on a rag and wipe away! Wear gloves, so you dont get it on your skin, it is very efficient in removing the oils off your skin, just like varsol would... any way, I hope this works for you.;
Good luck, Carlos....
HMS "Mighty Hood" and Lancaster "Dam buster" in progress......