There is little reason to break down the M1A on a frequent basis for as mentioned it is indeed a "clean" weapon compared to the 15/16 family of weapons. As for grease, that is the only thing to use on the rifle, no oil belongs on the weapon. Your receiver can use grease on the action rails, left and right, slight amounts and also on the back side of the two locking lugs, plus there is a third lug at the rear(small, but there if you look down on the action and to the rear of the bolt and on the left side) and a spot of grease there will not hurt. Place a smear of grease on the bottom of the bolt itself where it contacts the hammer as it travels. There is a groove machined on the right side of the action which captures the op rod as it moves back and forth and a tab rides in that groove- slight grease there.
The bolt has a roller surface which "cams" in the op rod and grease there will help as well. I also kept some light coating of grease on the op rod/spring component on these rifles-not heavy. The hammer is pinned into the trigger group housing and some grease at the pivot point is a good place for grease. While you are at it, I always felt the rifles shot better with a small amount of grease placed on the forward stock ferrel/cap and this helps any resistance from the stock and the gas cylinder assy. lip. Actually most match M1A's have the metal end cap polished and greased to avoid any change taking place during firing and give more concistantcy. Suggest you pick up the military maintenance manual which you can find at gun shows or order one. I can not remember the one which gives detailed instructions on the "care and feeding" of the M14/M1A, but it is out there and a great source of information. The M1A is indeed a very reliable rifle and will withstand a great deal of abuse and still deliver lethal, accurate firepower out to and including 800yds. Many feel it is the finest shoulder fired battle rifle ever conceived and of course others may not feel that way. In the hands of a skilled marksman, and even though you may well be downrange some 6-800yds, you had better keep your head down!!