the owner's manual for yer ltx 1040 should have engine oil capacity info similar to this paragraph from a lt 1042:
"IMPORTANT: On models LT1042 & LT 1045, the engine
(with oil filter) has a capacity of 1.5 liters (50.75 oz.). On
models LT1046 & LT 1050, the engine (with oil filter)
has a capacity of 2.0 liters (67.60 oz.). Never overfill the
engine crankcase."
May be different capacities on yer ltx 1040 (engine make/model)....
Using the mower's model # from the cavity under the tiltling seat, you can get a manual from the cub cadet website.