Dash Lights: The Oil Light on Your Dashboard

This is one dashboard light you don't want to ignore

Colin/Flickr

Your dashboard's instrument cluster has a light on it that either reads "oil" or looks like an old fashioned oil can. What should you do if you see this light while you're driving?

Don't ignore the oil light because it is an indication of a potentially serious problem.

Why Does the Oil Light Come On?

The oil light comes on when your engine suffers a drop in oil pressure. Without oil pressure, the engine can't lubricate itself, and the result is self-destruction, meaning you have to do some seriously expensive internal engine repairs.

You may be tempted to try to make it home or make it work, but an engine with no oil pressure is an immediate concern. It's almost guaranteed that you'll be rebuilding the engine if you don't address the low oil pressure as soon as possible. 

Why is Oil Pressure Necessary in a Car?

When your engine has enough oil in it, the oil pump is constantly pumping oil into all of the tubes that carry the oil to the parts of the engine that need lubrication. The action of the oil pump as it pushes the oil through the system builds up a certain amount of pressure.

This pressure makes all of the oil sprayers work internally. If there's not enough oil to keep up with the demand of the oil pump, you get periods of time, seconds even, when there isn't any pressure in the system. This may sound minor, but even a minute with no oil pressure can be enough to ruin an engine from the inside out. 

How to Check Oil Pressure

Before you make any major engine repairs, be sure to check the oil pressure sender to be sure your oil pressure is actually low.

It's best to have a repair shop do this because they can test the system from a few different angles to verify the results.

Other Causes of Low Oil Pressure

Another cause of low oil pressure can be a failing oil pump or a blockage in the system. Rarely does an engine become so gummed up that an oil passage is blocked to the point of reducing oil pressure, but it can happen.

More likely is the failure of the oil pump.

The good news is replacing an oil pump isn't the worst repair in the world. And if you've seen the oil light come on while driving, you should count yourself lucky that it was just the pump. 

If the oil light comes on when you're on the road, you should pull over as soon as it's safe and turn the engine off. While you're on the side of the road, you should check the oil. If it's low, go ahead and add some engine oil and see if it goes off. If not, it's time to take it to the shop. Better to spend a few bucks on an oil change now than to have to deal with a seized engine that can costs thousands of dollars later.