Use any of the white "lubriplate" grease or...
any of the teflon based. ("Plasati-lube")
Areas to use are the boltlugs & lugways, but not the rearfaces of the lugs, the firing pintang and upper edge of bolt, the inside cut-out on the Op rod hump, the bottom surface of the Op Rod handle and it inside surface, plus the tang of the handle and its fine channel in the receiver.
THe underside of the barrel, the Op Rod hooks and the corresponding hooks of the bullet guide(forward of the receiver) wipe your greasy fingers over thr interior parts (not a heavy coat) same with the Op rod Spring OD, and the area of the Op rod behind the gas piston, more to protect from corrosion from hot gases.
oil on the trigger and safety (Light coat)
A little is always better than a lot.
Note: oil anything that pivots/rotates, grease anything that slide.