Engine Oil Pressure

What is a good engine oil pressure?  Why is engine oil pressure important?

What is engine oil pressure?

Engine oil pressure is a measurement of the pressure behind the engine oil.

Why is engine oil pressure important?

Engine oil pressure is important because it is the driving force that circulates the engine oil through the engine to provide lubrication.  Without engine oil pressure, the engine oil would not circulate in a typical wet-sump engine.  Also modern gasoline powered engines often have features such as variable valve timing that require a certain minimum engine oil to operate cor

What is a good engine oil pressure?

Typical engine oil pressures for a gasoline passenger car engine with the engine oil at operating temperature is roughly 10psig per 1000 rpm (revolutions per minute) of engine speed.  However, engine oil pressure varies based on a number of factors, including (but not limited to):

Engine oil temperature vs. engine oil pressure

Engine oil generally gets thinner the warmer/hotter it is, and thus the engine oil pressure will decrease with increasing engine oil temperature.

Engine oil viscosity vs. engine oil pressure

In general, the thicker or more viscous an engine oil is, the higher the engine oil pressure will be.  Typical passenger car engine oil pumps have a relief at around 70-80psig to limit the engine oil pressure.

Mechanical condition of the engine vs. engine oil pressure

An engine with significant mechanical wear can decrease engine oil pressure.  Its oil passages and other tolerances may be beyond their maximum service limits, thus allowing more oil volume to flow than normal, which will thus decrease engine oil pressure.  If the engine oil pump is severely worn, it may not be capable of pumping the engine oil at the required volume and pressure.

Condition of engine oil filter vs. engine oil pressure

If the engine oil filter is severely clogged or is an inefficient design, the pressure drop across the filter may become excessive.  Most passenger car engine oil filters have a built in bypass valve that opens between 7 to 25 psid (depending on application) to protect the engine from lubrication starvation if the oil filter is plugged or during very cold weather startup conditions.

How is engine oil pressure measured?

This pressure is measured in units of force per unit area, such as pounds per square inch.  Sometimes the vehicle includes an engine oil pressure gauge so the operator can monitor the engine oil pressure.  Aftermarket engine oil pressure gauges can also be installed.

How can engine oil pressure be increased?

Assuming the engine is in good mechanical condition and not in need of repair, engine oil pressure can typically be increased by switching to a higher viscosity engine oil.  The vehicle's Owner's Manual can be consulted to see what engine oils the engine is capable of using.  But beware, although engine oil pressure is important, it is not the end of the line.  Read more about engine oil pressure here.