CFMs are oil drinkers. It's not uncommon to top up with about 4 quarts after a return 3 hr sector. And you have to pour the oil in slowly. Too fast and you end up with a puddle of oil on the floor. This has been resolved with the later ones though with a revised oil tank.
V2500 are much more fragile with a bird ingestion. A CFM could take in an Ostrich at take off and keep going, but if a V2500 swallowed a sparrow, it's a fan change.
Never done a fan trim balance on a CFM, only V2500, several times.