Cosmoline cleaning:
I researched a few boards and picked up some good ideas that I just used on my Yugo SKS.
WD-40 for the initial cleaning. It got a lot of the external cosmo off before I disassembled the gun.
Take down gun. Place all small metal parts in boiling water for 30 mins. Clean the inside of the stock with more WD-40.
I made a "soaking tube" out of 4' length of 4" PVC pipe. The top of the tube has a screw off cap and the bottom is permanently capped. Total cost of soaking tube: $20. Fill the tube with mineral spirits (about $2.75/gallon at local Home Depot) and insert the barrel/receiver. Take the small parts and soak in small pan of mineral spirits.
I let the metal soak for an hour or so. During this time, I took a heat gun to the stock. Cosmoline oozed out of every pore in the wood. When the cosmo stopped coming out, I wiped the entire stock down with mineral spirts.
Then I took the barrel/receiver out of the tube and scrubbed it down. I ran about 10 patches thru the barell. Next I scrubbed the small parts down. Then all the metal went back into the mineral spirts to soak overnight.
The stock got a nice light sanding with 220 grit sandpaper. Next, I coated it with Linseed oil. As linseed oil creates heat when it cures, you must be careful with the rags you use to apply it. They can spontaneously combust. So set them outside (not in a pile of dry leaves ) for a day or two before throwing them out.
Next day, I took out the barrel/receiver and scrubbed it again. This time, I blew compressed air into all the small nooks. Same deal with small metal parts. After the mineral spirts had dried, I applied a coat of G96 and re-assembled the gun.
Total time invested was about 5 hours (not including trip to Home Depot).