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Does Synthetic Oil Turn Black? (Read This First!)

Synthetic oil is very popular among those vehicle owners who don’t hesitate to spend some extra penny for the betterment of their transport. It’s a bit costly but much more effective than regular oils.

While users are satisfied with the enhanced performance synthetic oil provides, many get concerned as they notice the oil getting darker and black. Some even doubt the authenticity of the oil.

So does synthetic oil really turn black? Here we’ve prepared the answer along with more information you might like to hear.

Does synthetic oil turn black?

Synthetic oil turns black just like any other engine oil. It’s naturally dark in shade and darkens due to many reasons. Oxidization, heat, dust, deposit, etc. cause synthetic oil to turn black mostly. However, black synthetic oil doesn’t always indicate oil change unless there are other signs.

Synthetic oil is one of the best oil to maintain the condition of a vehicle. It’s more effective than conventional oil and helps to extend the vehicles’ life by protecting the motor and engine parts.

Synthetic oil does the same job as other engine oils. But it is different by its appearance. The color of synthetic oil is darker than conventional or regular oil.

It’s more deep than golden, nearly toffee or amber color. And over time, this shade too darkens and turns black.

Oils turning black is not unusual. It can happen due to many reasons. Synthetic oil similarly turns black after some time as some of the factors such as oxidization, heat cycle, dirt, dust, soot, etc. affect it. 

Discoloration because of these reasons is quite normal because it doesn’t ruin the quality of the oil.

While synthetic oil can turn black and requires no change in most cases, sometimes the alteration in color indicates to oil change. It then gets thicker, unclear as well as too dark.

Let’s know not whether both kinds of synthetic oil turn black:

Full synthetic oil:

Full synthetic oil is different in its’ manufacturer process.  It contains the same mineral oils as the base but is more refined and filtered.

So it is more synthetic and less contaminated. However, that doesn’t prevent it from getting darker or black.

Since it possesses the same characteristics as regular synthetic oil and does a similar job, it too turns black.

Semi-synthetic oil:

Semi-synthetic oil turns black as after several usages it traps dirt, dust from the air as well as metal particles from the engine.

Moreover, similar to regular synthetic, semi-synthetic oil it oxidizes, goes through heat and so discolors gradually.

Is synthetic oil black?

Synthetic oil is not purely black in its cleanest state. It can be tagged as toffee or amber in shade, which is darker than regular oil. But synthetic oil is not fully black generally.

Synthetic oil usually is darker than regular conventional oil. It’s close to amber or toffee color. The pure synthetic base can be clear but when freshly poured from the bottle it’s dark and transparent with added dye.

However, synthetic oil can turn darker over time. It’s because of the additives in it. Those additives make the oil attract more dust, and grime thus the color darkens after a time. This is normal and doesn’t mean you’ve to change the oil.

But if the density of synthetic oil changes into a thick liquid while the color is darkening, it’s a sign to change in the oil. Otherwise, synthetic oil may turn black normally.

Why does my synthetic oil turn black?

Synthetic oil is dark in color, unlike conventional oil. Over time, it darkens more which can be the result of many factors.

Take a look at the possible reasons why your synthetic oil turns black:

It contains additives:

Synthetic oil contains additives or chemical particles so that it can boost the engines’ performance. And additives darken the color of the oil. Moreover, it attracts more dust, grease so the oil eventually turns black,

It’s heated:

A vehicle goes through multiple heat cycles every day. As it activates the engine and crosses miles, the engine heats up from 190 degrees to 220 degrees.

Synthetic oil used in the engine too gets heated up through this procedure. When the vehicle is not on the run, the engine cools down, the same happens with the oil. Thus the cycle continues and transforms the oil into dark black color.

It’s not clean:

Another common reason your synthetic oil is changed into black is the buildup of dirt, deposit, and soot. After a certain time, the oil gets overloaded with polluted particles and buildup forms in various parts of the engine.

Also, a grimy oil filter, tiny metal dots, etc. turns synthetic oil black.

It’s oxidized:

Oxidization is a major reason synthetic oil discolors. When being used in an engine the oil comes in contact with the air consisting of oxygen.

The oxygen molecules when get together with oil particles, the oil reacts to the chemical clash.  turns black.

How long does it take for synthetic oil to turn black?

Synthetic oil is generally darker than conventional oil. It’s not black usually but can turn black after some time.

The timing of synthetic oil to darken depends on many factors such as the amount of buildup, dirt and grease, heat, and the brands of oil too. In general, after 3000 to 5000 miles’ synthetic oil starts darkening.

Synthetic or conventional, oils are meant to darken when contaminated with dust, soot, etc. Also, the discoloration can happen due to a large amount of heat. Moreover, over time as you use the vehicle regularly, synthetic oil might turn black very soon.

It usually takes 3 to 6 months of use for synthetic oil to turn black. It’s normal behavior and needs to step to be taken. But if the consistency too changes along with the color, you might need some expert advice.

What color is synthetic oil when it needs to be changed?

Synthetic oil is naturally darker in color. Top over that, its’ color deepens over time due to various reasons. Synthetic oil, that’s actually dark toffee or amber in color, turns black in the first place due to oxidization. 

Frequent and regular use of the vehicle to darken synthetic oil. Moreover, dust, grease, heat cycle, and additives too play their roles to darken the oil.

If your synthetic oil discolors due to the mentioned reasons, it’s very normal. It can turn dark to kohl black but you don’t need to change the oil always noticing the color. Because discoloration is not an indication.

The discoloration is a common behavior of synthetic oil and it doesn’t mean you have to change the oil. You should change the oil only when you see differences in the oils’ color and in their appearances. 

How do you know if engine oil is bad?

To know the state of the oil, good or bad, you must read some signs. Let’s know what signs indicate the engine oil is no anymore at its finest state.

Dark and thick oil:

The appearance of the engine oil is an easy-to-observe sign to know if the engine is on a good term.

If you see the oil is darker than usual and also thicker and unclear you should be alert. Bad engine oil is too thick in consistency and also not transparent.

Noisy engine:

Oil works as a barrier between the parts of an engine. It lubricates the metal brush, parts so they don’t engage with each other making noise.

If the oil isn’t at its best, it can’t lubricate enough thus the engine parts collide and makes the engine loud.

Oil smell:

Oil smell inside the vehicle is another signal you should think about changing the oil. This happens because of an oil leak.

Engine oil leaks when the oil plug is not strongly attached, the gasket is faulty or there is any damage to the oil filter, gaskets, or oil sending unit. It means it’s time the oil is changed.


You should change the engine oil when you’ve reached a certain mileage which is different for a different vehicle.

You can figure this out by checking the last mileage sticker or from the miles you’ve traveled. Generally, it’s best to change the oil after 3000 miles.

Final Thoughts

Synthetic oil discolors and gradually can turn black. One of the reasons is the additives in it that trap more dust and dirt. Heat cycle, soot, and deposit buildup, oxidization too are responsible. Synthetic oil needs to be changed when it shows more signs along with major discoloration.