* Engine size: A larger engine will generally have higher oil pressure than a smaller one. A 78 Silverado could have several different engine options (e.g., small-block V8, big-block V8, inline-6).
* Engine RPM: Oil pressure increases with engine speed.
* Oil temperature: Hotter oil is less viscous and will result in lower pressure.
* Oil viscosity: The weight of the oil (e.g., 10W-30, 20W-50) significantly impacts pressure. Using the wrong viscosity can drastically alter readings.
* Engine wear: Worn bearings and other internal components will lead to lower oil pressure.
Instead of a specific number, look for these guidelines:
* At idle (warm engine): You should see at least 10-15 PSI. Lower than that could indicate a problem.
* At operating temperature and 2000 RPM: You should see 30-50 PSI or more, depending on the engine and oil viscosity.
* Consistent pressure: The gauge should show a relatively steady pressure across the RPM range, not fluctuating wildly.
To find the best information for *your* specific 1978 Chevy Silverado:
1. Check your owner's manual: This is the best source for the manufacturer's recommendations.
2. Consult a repair manual specific to your engine: These manuals often provide oil pressure specifications based on engine type and RPM. Chilton and Haynes are common brands.
Important Note: Always address low oil pressure promptly. Driving with low oil pressure can severely damage your engine.
