What does it mean when the oil can light comes on?

[MatthewLynn]

The reasons for the oil can light coming on are as follows: 1. Insufficient engine oil volume reduces the oil pump's output or prevents it from pumping oil due to air intake, leading to a drop in oil pressure. 2. Damage or failure of the return valve: If the main oil passage return valve spring is fatigued, softened, improperly adjusted, or if the valve seat and steel ball mating surface is worn or stuck by debris causing improper sealing, the return oil volume will significantly increase, and the main oil passage pressure will drop accordingly. 3. Incorrect oil selection: Using the wrong oil or an inappropriate grade can cause increased leakage due to low oil viscosity during engine operation, thereby reducing oil pressure.