How can you tell what weight of oil is in a shock? One simple method is to compare its flow rate to known weights of shock oil. We do this using a â€œpaint viscosity meterâ€, a small plastic cup with a specific size hole in the bottom. Fill the â€œmeterâ€ with oil, holding the exit hole shut, and record the amount of time it takes the cup to drain. Assuming all of the shock oils are at the same temperature, the lighter weight oils will drain faster, the heavier weight oils will drain slower. You should be able to quickly determine what weight oil is inside any shock by comparing its flow time to that of a known shock oil.