Clean vs Dirty Engine Oil Comparison

clean vs dirty engine oil
Check the color and level of engine oil using a dipstick | Freepik

Engine oil is something you should pay attention to. It’s the blood of your car and should be changed regularly, according to the manufacturer’s schedule. However, some people don’t change it as frequently as they should, leaving dirty oil or, worse, running at a very low oil level.

If you’ve ever wondered how to check if your engine oil is dirty or clean, we’ll help you distinguish clean vs dirty engine oil.

What is the difference between clean oil and dirty oil?

Engine oil is the lifeblood of your car. It keeps all of the moving parts in your engine lubricated and protected from friction and heat. Over time, engine oils can get dirty and reduce their ability to protect your engine. This is true for all brands and types of engine oils.

Clean vs dirty engine oil

clean vs dirty engine oil

Clean engine oil will have a slightly translucent amber or gold color. Clean engine oil has also a higher viscosity than dirty oil. Dirty engine oil will be darker in color and less viscous. As viscosity decreases, so do lubrication capacity, leading to increased wear on critical components.

It’s normal to see oil color change without experiencing any issues. In fact, ExxonMobil engineers have found in numerous cases that oil can change color and yet have no impact on its performance. Although the characteristics of engine oil differ among brands, there are some common standards you can use to determine whether or not your car needs an oil change.

For example, most manufacturers recommend changing your engine’s oil every 5,000 to 7,500 miles. You can check your manual for details on how often you should change your car’s engine oil.

Related post: Can You Mix Fully Synthetic With Semi Synthetic Oil? 

What is considered dirty engine oil?

Dirty engine oil is engine oil that does not meet the specifications for quality. It can be caused by many things, including poor fuel quality and insufficient oil change intervals. Here’s what a dirty engine oil looks like on a dipstick:


The color of the oil is an indication of how many metal particles are in it. Over time, engine oil turns dark to black. The darker the color, the more metal particles there are in your engine.

This can cause problems with your engine’s performance and longevity because these particles can get stuck in other parts of your vehicle’s engine and cause damage over time.


Dirty engine oil is the one that has lost its viscosity and can become sludgy, grainy, or even too thick. The reason why dirty engine oil becomes dirty is that it contains deposits of metal shavings, dirt, and carbon particles.

Dirty engine oil isn’t just visually unappealing; it loses its viscosity over time as well. The oil won’t flow through your engine as easily anymore, leading to decreased performance and overall wear and tear on your vehicle.

Related: Oil in the Spark Plug Well – Causes and DIY Fix

What should clean engine oil look like?

Clean engine oil protects your engine from wear, prevents corrosion and contamination, and ensures that all moving parts are lubricated. The texture of your engine oil can vary depending on the brand or type you use, but here’s what a dirty engine oil looks like on a dipstick:


The color of clean engine oil varies depending on brand and type. You may have noticed that different brands or types of oil have different colors, ranging from golden amber to reddish-brown. This is simply due to the additives used in each brand.

The basic idea behind this is that when there are few contaminants present in the oil, it will appear clear or slightly translucent; when there are more contaminants present, it will take on a darker shade of amber or caramel-hued color (depending on how much carbon is present).


There are many different brands and types of engine oil. The texture differs per brand or type, but in general, new and clean engine oil should be smooth when poured from the bottle. Clean engine oil is glossy and somewhat transparent. It should not have visible grime or contaminants.

If you notice any particles floating around in the liquid or if it appears cloudy or has dark or black color, then it’s time for an oil change immediately.

What are the symptoms of dirty engine oil?

There are a few ways to tell if your engine is dirty.

  1. Check the dipstick -First, you can check the dipstick (the stick that shows you how much oil is in your car). If it’s dirty (dark or black), then your car needs a new oil change.
  2. Knocking sound from the engine -Secondly, you might hear knocking or other sounds coming from your engine that wasn’t there before. This is caused by wear and tear on the pistons and other parts of the engine that need lubrication to work properly.
  3. Smokier exhaust – Lastly, if you notice black exhaust smoke than usual coming out of your tailpipe while driving, that’s another sign that there’s something wrong with your current level of oil.

Dirty engine oil causes

The most common cause of dirty oil is ash picked up from the walls of your engine’s cylinders. As your engine burns gasoline, it creates soot that attaches itself to the walls of the cylinder — this is called “carbon” or “ash.”

Also, as oil cycles through your engine, it collects contaminants like bits of metal and carbon from inside the combustion chambers. These contaminants can clog up the filter on your car’s oil pump, which means less clean oil gets pumped out to lubricate all moving parts within your engine.


This article illustrates clean vs dirty engine oil. Clean engine oil plays a critical role in keeping internal engine components lubricated and happy. Dirty oil, on the other hand, can cause everything from engine wear to complete failure of critical components such as pistons and cylinder heads.

If you take your car’s maintenance seriously, be sure to check the color of your engine’s oil every time you fill the tank. And don’t wait for it to look dirty: change it regularly to prevent damage and guarantee that your engine will run smoothly off the lot and for years to come.

Elevate your car maintenance game by reading our comprehensive guide on engine oil. Learn everything from the basics of oil types, to how to properly maintain and change it. Keep your vehicle running at its best, read our guide now!

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