* Engine RPM: Oil pressure increases with RPM.
* Oil Temperature: Pressure generally drops slightly as oil temperature increases (within normal operating range).
* Engine Wear: Higher mileage engines might show slightly lower pressure than newer ones.
* Oil Viscosity: The weight of the oil (e.g., 10W-30, 20W-50) significantly affects pressure. Thicker oil yields higher pressure.
However, a generally accepted minimum oil pressure for a 305 Chevy at idle (around 600-800 RPM) is 10-15 PSI. At higher RPM (around 2000 RPM), you'd expect to see significantly higher pressure, typically in the 30-50 PSI range.
Crucially: These are just guidelines. Always consult your owner's manual for the specific oil pressure recommendations for your particular year and model of vehicle with the 305 engine. Low oil pressure, consistently below the minimum, indicates a potential problem requiring immediate attention.
