[Whiskey]

It will depend on the gun that you have, here is an example from Mares for different types of their guns; on average you can see the small guns use 15-20 cc medium 25 cc and the large 30cc. I have never been that accurate in the amount of oil I put in.

USE ONLY CORROSION AND RUST PREVENTING OILS, SUCH
AS MOBIL DTE OIL LIGHT OR SAE 10 W OILS SUITABLE FOR
USE IN HYDROPNEUMATIC SYSTEMS. DO NOT USE GRAPHITE
BASE OILS! THE USE OF OILS NOT SPECIFIED FOR USE IN
HYDROPNEUMATIC SYSTEMS MAY LEAD TO PREMATURE GUN DAMAGE DUE TO INTERNAL CORROSION.
SPEARGUN OIL QUANTITY IN CC
STEN MINIMINI -15
STEN MINIMINI -20
STEN MEDI -25
STEN -30
SUPER STEN -30-
SPEARGUN OIL QUANTITY IN CC
CYRANO 550 - SPARK 550 -20
CYRANO 700 - SPARK 700 -25
CYRANO 850 - SPARK 850 -25
CYRANO 970 - SPARK 970 -30
CYRANO 1100 - SPARK 1100 Pipin -30" Mares Manual 2002