Engine oil is circulated through your engine via an oil pump. Your oil pressure is higher when your oil is thicker or there is an obstruction in an oil passage.
There are also times when high oil pressure is normal and no cause for concern. Here’s how you can know the difference.
Normal Causes of High Oil Pressure
1) Cold Start
When you first start your engine, your oil pressure will be pretty high. This is because the engine oil is thicker at ambient temperatures than it is at operating temperature.
2) High RPM
The oil pump is driven by the engine’s crankshaft. As the engine spins faster, the oil pumps harder (just like your heart when you go for a run). Oil pressure naturally increases as you rev up the engine. Your car is designed to work this way to make sure your engine is adequately lubricated under load.
3) Low Ambient Temperatures
The colder your oil, the thicker it will be. When it’s cold outside, your oil will be even thicker than usual, particularly on cold start.
If you have trouble starting the vehicle in the cold, try switching to an oil that is thinner at ambient temperature. This is the number to the left of the W. For instance, try 5W-30 instead of 10W-30 in the winter time.
Problematic Causes of High Oil Pressure
1) Obstruction in an Oil Passage
Debris inside the engine has the potential to block thin oil passages in the cylinder heads and engine block. Any blockage in an oil passage can hinder the flow of engine oil, raising oil pressure.
This is a potentially serious problem. A blockage can restrict or inhibit flow to a section of the engine. This means part of the engine is insufficiently lubricated, which leads to excess heat and wear. In extreme cases, catastrophic failure may result.
2) Dirty Engine Oil
If you run your oil for too long without changing it, your oil will get dirtier over time. As your oil gets dirtier, it will gradually get thicker from the carbon and other deposits it collects from the engine. In extreme cases of neglect, your engine oil will start to turn into a thick sludge that gums up the inside of the engine.
It typically takes 10,000 miles or more for this sludge to accumulate. Some full synthetic oils are actually designed to run up to 20,000 miles under certain conditions, and may be perfectly fine running for 10,000 miles with no sludge present.
Do keep in mind that both the engine and the oil have to be designed for oil change intervals of this length. Even then, the environment and driving style will be important factors in an extended oil change interval.
3) Wrong Oil Viscosity
Running a thicker oil will raise oil pressure under the same operating conditions. Sometimes this is desirable. For instance, towing or racing on a hot day will generate significant heat for the engine. A hotter engine will thin out the oil. Some drivers compensate for this by running a thicker oil under certain conditions.
Running an oil that is too thick will increase oil pressure too much. This could potentially restrict the flow of the oil, leading to the same oil starvation issues you would see if you didn’t run enough oil in the engine.
How Do I Know if My Oil Pressure is High?
On most vehicles, you won’t really know what the oil pressure is unless there is a problem. In the vast majority of cases, if you don’t see a warning light, don’t worry too much about oil pressure.
If you really want to check your oil pressure, there are oil pressure testing kits you can buy that will help you determine if your oil is in a normal range. Additionally, there are aftermarket gauges that you can hook up to your oil supply that will tell you what your oil pressure is while you’re driving.
Real Oil Pressure Gauge
Most of the time you’ll never know exactly what the oil pressure is, but some vehicles have a real oil pressure gauge that shows you the oil pressure in real time. It’s not uncommon for drivers to be concerned when they see high oil pressure, which is why real oil pressure gauges have been phased out over time.
When looking at one of these gauges, keep in mind that it’s normal to see very high oil pressure right after you first turn on the car, and for about 10 minutes when you first start driving.
If you have concerns that your oil pressure reading is different than you expected, check online forums for your specific year, make, and model and see what numbers other owners of the same vehicle are experiencing.
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