I probably average two stocks per month for customers......I use lacquer thinner then acetone in a plastic bath with an air tight lid, slightly larger than the average stock........
1. Weight the stock in the bath so it is submerged (I use a brass 1" solid rod 8" long for this), leave 24 hours....remove and let air dry.....if oil remains, submerge again for 2-3 hours.....remove and let air dry....repeat this process as needed to remove 100% of the old impregnated oil.....clean the checkered areas lightly and gently as needed with a small brass brush as the dip process proceeds........
2. For a second cleaning bath, use a second plastic sealed bath only this time filled with acetone.....(or use the same plastic sealed bath after cleaning).....the stocks usually sink in acetone but I weight them with the same brass rod anyway, leave an hour or two with the lid secure...remove and air dry, which is fast with acetone.....check for any oil bleed.....then repeat as necessary, including back to the lacquer thinner bath if need be.......then leave overnight in a warm enviornment and watch for any oil bleed......
3. Stocks will not crack with this process.....I never use alcohol or oven cleaner....... The stock should now be ready to repair-epoxy-pin-clamp or stain and refinish, rechecker, steam dents or whatever.......patience is the key here......
4. If you have a stock with a modern polyurethane finish, like some Beretta's and Brownings, then you will need to use aircraft paint stripper first to remove the poly coating....
Best,