I need help!

I am the owner of a 2011 Mitsubishi Lancer Ralliart. It only has 4,800 miles. I purchased the car from an auction and thus the car is now restore salvage. The car was hit in the front, but I fixed it; however, I still have a problem with the AWC pump because whenever I put oil inside the AWC pump, it empties out within 20 miles. This oil somehow ends up in the transmission in the transfer case. This oil mixes with gear oil. Then the tarmac, gravel, snow option starts blinking and then disappears from my dashboard. This is immediately replaced by a yellow triangle with a "!" inside and under it says something about 4-wheel drive service required. Nothing else is wrong with the car and I'm surprised at having this problem since the car was perfect in the back and since it is so new. Can I take off the front transmission case (AYC) without taking off the engine or transmission because I wanna see if a piston is broken or not which causes the oil mix (SPIII mixes with LCD transmission gear oil) or is the AYC pump running continuously? Please let me know if you have any ideas or if you have had similar problems. Ask for more information if needed. I am also thinking of selling this car, how much do you think I could sell without fixing this problem. The car works fine aside from the AWC option no longer being there for now.