* Engine RPM: Oil pressure will be higher at higher RPMs.
* Oil temperature: Hotter oil will be thinner and have lower pressure.
* Oil viscosity: The weight of the oil (e.g., 10W-30, 20W-50) significantly impacts pressure. Using the wrong weight can lead to inaccurate readings.
* Oil pump condition: A worn oil pump will produce lower pressure.
* Engine wear: Excessive engine wear can also lower pressure.
Instead of a specific number, look for these guidelines:
* At idle (warm engine): You should see at least 10-15 PSI. Lower than this could indicate a problem.
* At operating temperature (around 2000 RPM): You should see 30-40 PSI. This is a typical range, but it can vary slightly depending on the factors listed above.
* At higher RPMs (3000-4000 RPM): Pressure should increase, but excessive pressure (significantly above 60 PSI) could also indicate a problem.
What to do:
1. Check your owner's manual: While it might not give exact numbers, it may give a range or general guidance.
2. Consult a repair manual specific to your 1990 Mustang GT: These manuals usually provide more detailed specifications and troubleshooting advice.
3. Use the correct weight oil: Check your owner's manual for the recommended oil viscosity for your engine.
4. Monitor your oil pressure gauge: Regularly check your gauge while the engine is running to get a feel for its normal operating range. Any significant drop in pressure should be investigated immediately.
If you are experiencing consistently low oil pressure, it's crucial to address the issue promptly to prevent serious engine damage. This could involve checking the oil pump, oil filter, oil passages, and other components. Professional diagnostics are recommended if you're unsure about the cause.
