What is the minimum idling oil pressure?

What is the minimum idling oil pressure?

• A. 20 PSI
• B. 25 PSI
• C. 15 PSI
• D. 30 PSI

Answer: (B)

Minimum idle oil pressure ensures enough lubrication at the lowest engine speed. When the engine is idling, the oil pump runs slowly, so the pressure drops. A defined minimum protects bearings and other moving parts from excessive wear at low RPM once the oil is warmed up. For many engines, the acceptable minimum at idle with normal oil temperature is 25 psi. Readings below that—such as 20 or 15 psi—would indicate inadequate lubrication risk, while 30 psi is simply above the minimum. Therefore, 25 psi is the correct minimum value.

Minimum idle oil pressure ensures enough lubrication at the lowest engine speed. When the engine is idling, the oil pump runs slowly, so the pressure drops. A defined minimum protects bearings and other moving parts from excessive wear at low RPM once the oil is warmed up. For many engines, the acceptable minimum at idle with normal oil temperature is 25 psi. Readings below that—such as 20 or 15 psi—would indicate inadequate lubrication risk, while 30 psi is simply above the minimum. Therefore, 25 psi is the correct minimum value.