Answer:

OILS

Answer	Crossword Clue
OILS	Makes slippery
OILS	Monet's output
OILS	Squelches a squeak

OILS	Greases
OILS	Liquid squirts?
OILS	Monet medium
OILS	Olive and corn
OILS	Butter alternatives
OILS	Makes slick
OILS	Portrait medium
OILS	Van Eyck's medium

OILS	Gives a lube job
OILS	Many old masters
OILS	Many Rembrandts
OILS	Old masters, often
OILS	Studio supplies
OILS	Art collection, maybe
OILS	Aromatherapy supplies
OILS	Masseuse's assortment

OILS	Rijksmuseum collection
OILS	Canvas colors?
OILS	Some palette colors
OILS	Some paintings
OILS	"Mona Lisa" and "Girl With a Pearl Earring," e.g.
OILS	Artist's choices
OILS	Lubricates
OILS	Artist's medium

OILS	Monet works
OILS	Makes quieter, in a way
OILS	Museum works
OILS	Some Met works
OILS	Works at a museum
OILS	Masseur's stock
OILS	Some gallery hangings
OILS	Cooking aids

OILS	Masseur's supply
OILS	Some Van Gogh works
OILS	Works at the Louvre
OILS	Cook's array
OILS	Makes less squeaky, perhaps