Torah Temimah cites Menachos 60a.
“He shall not put oil upon it” — if he put oil on its leftovers (after kemitzah), he does not transgress a negative commandment; Scripture is speaking of the body of the minchah itself (the kometz that is offered).
Miyut of “aleha” to the offered portion — the lav attaches to the flour that is to be burned, not to the remainder.
Oil mixed into the sheyarei minchah after the kometz has been removed does not trigger the prohibition. The ban targets only oil on the portion destined for the fire. The Torah’s language “upon it” is read as referring to the body of the offering that ascends the altar.