How To Check Engine Oil Quality? – A Complete Guide


If you love your ride either it is a car, a bike, or any other you must have to care for its engine. One of the most effective ways to care for your car engine is to maintain the engine oil quality. Because, if the engine is the heart of a car, then engine oil should be its bloodline.

Engine oil is a lubricant that is added to your car engine to avoid its parts to wear down due to friction. It provides a thin liquid film between the engine parts and prevents it to wear down.

It is necessary for a ride’s owner to always add the best quality engine oil to his car or bike. Except for it, it is the main responsibility of the owner that to maintain the engine performance, check the engine oil quality from time to time, and keep it maintained.

Why do we need to check engine oil quality?

As mentioned above that the engine oil is the bloodline of your car’s engine. It provides a thin film between the engine parts and protects them to wear and tear.

As much as the car run, it covers the distance and after thousands of kilometers, the engine oil gets dirty due to its regular functioning in the engine. It collects debris and contaminates while moving in the engine parts. So we need to replace it.

Factors affecting engine oil changes

The right time to check your engine oil quality and its time to change can be based on different factors, that are:

  1. How you drive your car?
  2. Where you drive your car?
  3. How many miles you’ve driven so far?
  4. How long it has been since your last oil change?

If you want to maintain your car’s engine and need to get maximum efficiency from it regarding the engine oil, these are the most important questions you must be aware of.

But the question is how to check the engine oil quality?

So we have summed up some important information regarding the engine oil’s durability and quality that every rider should be aware of.

How to check the quality of engine oil?

In answer to the upper question, there are two approaches to check the engine oil quality.

1. Chemical Method:

Used to check the engine oil quality internally in its composition.

2. Physical Method:

Used to check the engine oil quality simply by physical method.

1. Chemical Method

The two most important factors that play a significant role to check the engine oil quality chemically are:

1. Engine Oil Viscosity

2. Engine Oil Volatility

1. Engine Oil Viscosity

In general term “viscosity” can be defined as the resistance of any liquid to flow. In simple words, we can say that viscosity is a tendency of the oil with which it will keep itself in between the engine components by making a thin film and protect the engine’s wear and tear.

Viscosity is the most important feature of engine oil. It determines how your engine lubricant will react in response to change in its speed, pressure, and temperature.

Viscosity and engine health

When the surfaces of engine oil are brought closer in relative motion under pressure, the viscosity of engine oil prevents it to escape too quickly due to high molecular friction between the oil. The greater viscosity of oil that enables it to stick with the surface and the level of incompressibility keep the running engine surfaces apart from each other and hence aid to prevent wear. This is called hydrodynamic lubrication.

The higher the viscosity, the higher the attraction will found between oil molecules and ultimately higher the wear prevention.”

Engine oil viscosity from a historical point of view

Early in the ages, engine oil was simply made and formulated on newton’s equation of viscosity. The higher the force exerts to flow the oil (shear stress), the higher its flow rate (shear rate). Viscosity – the ratio between shear stress to the shear rate remained the same at all shear stress.

The engine oils of that time were simply of single grade and did not contain any SAW “W” classification.

Later in the 1940s, it was discovered that adding a small amount of high-molecules polymers can help the capacity of engine oil flowing conditions. It can flow and maintain its viscosity in both starting (low temperature) and operating conditions (high temperature).

Now, these polymer-containing oils were classified by SAW as multigrade engine oils because it was considered best and highly suitable for both viscosity-temperature zones. These oils were originally produced to lower the viscosity of engine oil at lower temperatures i.e. at the time of engine startup. Since then, these multigrade oils e.g. 10W-40, 0W-20, 5W-30 become very famous and create their space very soon.

Most of the automobiles and engine oil companies recommend these multigrade engine oil in their vehicles. But it advised that you have to consult your vehicle’s manual first to check the recommended oil grade while changing the engine oil.

Drawbacks of oil viscosity

There is great worth of engine oil concerning its viscosity but there are also some negative aspects of viscosity that can affect the efficiency of engine operation.

The oil’s molecules friction is the main cause of its viscosity also compels the engine to exert more force to overcome this molecular friction while the movement of its parts, and thus reduce its efficiency. This is the force that an engine has to be exerted is exchanged for its wear protection.

Therefore, every engine requires a perfect and suitable weather condition engine oil formulation concerning its viscosity for both lower and upper temperatures. It is the most critical point for selecting an engine oil for a vehicle’s owner.

Lowering the engine oil viscosity can be an important step to improve fuel efficiency by reducing viscous friction. Fortunately, over the past years, engine oil companies all over the world are trying their best to reduce oil viscosity which helps to improve the engine/ fuel efficiency, but only in engines that are designed for their use.

2. Engine Oil Volatility

Another aspect to check the engine oil quality is its volatility. It was observed that the viscosity of the engine oil cause reduction in fuel efficiency as well as engine performance. Engine oil companies also use different heavy metals and catalysts in the oil to improve the viscosity which also causes heavy smog production.

To reduce the viscosity in engine oil formulation, the manufacturer uses base oil with higher volatility. It improves the volatility of engine oil which allows the oil to volatile at low temperatures and start its function properly.

“Due to higher volatility, the engine oil easily becomes thinner and circulate easily. It also improves fuel efficiency and heat-absorbing ability”

Engine Oil Volatility and Catalytic Converter

Another aspect of using the high volatile engine oil is that it lowers the amount of energy used by the catalytic converter in the engine. The catalytic converters are the substances found in your vehicle, mostly in the silencer, that speed up the reactions and secondly convert the highly toxic and polluted gases (smog) (SO2, NO2) produced by the engine into less toxic and less polluted gases (such as N & S).

When we improve the volatility of the engine oil, it means we are lowering its viscosity at an optimum level without compromising on its quality. So in the end, the catalytic converters will exert low force on the smog due to the short amount of toxic and polluted particles in the engine, hence engine efficiency improves.

To maintain the volatility of the engine oil we have to maintain the oxidation and thermal stability of the engine oil.

“Generally, the engine oil volatility must be less than 13%.”

2. Physical Method

The common method to check the engine oil quality manually is the physical method.

In most cars, there is also a light indicator of engine oil on the dashboard. The light indicator warns you about the oil condition but it’s better to check the engine oil manually once a week.

Part I – Checking the Engine Oil

1. Make sure the engine is not hot:

First of all, you need to sure that the engine is not hot. Don’t try it right after driving the car. If you check the oil while the engine is hot, you can harm yourself. Wait at least 10 minutes or try to check the oil when the engine is cool.

“When the engine is cool, the oil should get enough time to settle down at the bottom of the engine pan, and you will find an accurate reading that how much oil is present in the engine.”

2. Stand the vehicle at a level surface

Always stand your car at a level surface. At the level surface, the engine oil’s surface remains level and you can find an accurate quantity of oil present in the engine while checking it by dipstick.

A car parked at a level surface to check engine oil

3. Checking the engine oil by dipstick

Open the bonnet of the car and pull out the engine oil dipstick connected with the oil tank. You will found it at the front of your car’s engine. Try to pull out the right oil dipstick, instead of pulling out the transmission fluid dipstick.

The Mechanic is Pulling-out the oil dipstick to check the engine oil
The mechanic is wiping the oil dipstick with a cloth.

If you can’t find it, check your car’s manual or consult with any technical person at the oil refill station.

The dipstick splashes with the oil while in motion, so after pulling it out once, wipe it with a cloth to clean and reinsert it in the same pipe from where it is pulled out.

Push it all the way down until it is fully reinserted. If it is getting hurdle or stuck while inserting, pull it a little bit back and try once again. Try to keep it fully straight while inserting it. Now pull out the dipstick again from the pipe and check the oil film line on it.

There are different indication marks on the different dipsticks. Sometimes there are holes at the end of the dipstick to check the oil level, and sometimes there are written marks like “F” for FULL and “L” for LOW or ‘”A” for ADD.

Look at the ‘F’ & ‘L’ mark or holes on the dipstick to check the engine oil.

4. Checking the quantity of the oil

  • If the oil film reaches near or below the LOW/ADD mark or at the last hole from the bottom side, you need to add the engine oil.
  • If the oil film is found near the FULL line or at the top hole from the upper side, you don’t need to add more oil.

5. Checking the quality of the oil

Besides checking the quantity of the oil, you have to check the quality of the engine oil also.

The color of good quality oil should be dark brown. Try to rinse the oil in between your fingers, it should be vicious and plain. If the color becomes light or full back, or it feels that oil contains debris and contaminants by rinsing in between your fingers, it should deteriorate and it’s better to change it with a new one.

6. Put the dipstick back into its pipe

By analyzing your engine oil quality and quantity, reinsert the dipstick back into its pipe either you are going to add more oil to the engine or not.

Part II – Add oil to your engine

7. Find out the accurate kind of oil to be used

First of all, make sure which engine oil type you have to use in your car’s engine. To know this, consult your vehicle’s manual. Then purchase it.

8. Open the oil filler cap

After checking the engine oil quality, open the oil filler cap located at the front of the engine – a few inches away from the dipstick. Don’t mistake putting the oil into the same dipstick pipe. If you don’t find the cap, try to check its position in the car’s manual or ask an expert.

9. Pour in the oil

Now add up the engine oil at the necessary level. You can use a clean funnel to pour in the oil or add it up directly by turning the container upside down. After adding up to the F mark, close the filler cap again tightly.

The mechanic is adding engine oil

10. Recheck the oil level

Now check the oil level again with the dipstick by repeating the upper procedure. Make sure that oil film reaches the “FULL” mark.

What is the best time to check the engine oil?

It’s better to check the engine oil in the morning time when the engine is cool and the oil is settled down lower in the engine pan. So that accurate engine oil quantity can be checked by dipstick.  However, it is also recommended that must check your engine oil before going on a long drive.

Why we even need to get an oil change?

Engine oil runs your engine smoothly and reduces friction. While checking the engine oil make sure that there’s enough engine oil present there. Besides checking the quantity of oil, also check its quality.

Dirty oil can’t perform as well as fresh oil does. The additives in dirty oil boil out, water collects over time, and forms sludge. As the oil gets old, it holds the abrasive particles suspended in it that cause the wear away of the engine parts instead of protecting it. So it’s time to change your old oil to a fresh one.

Recommended time to change engine oil

It is considered good that keeps your engine oil fresh and updated. However, changing the engine oil frequently is also not recommended itself. Changing the oil early will not affect engine efficiency, but it will hurt your wallet.

It is mandatory for every vehicle’s owner that he must know about the recommended time of oil changes. For this purpose, he must consult his car’s manual.

It was recommended that change your engine oil after 3000 miles or after 3 months. But now with modern lubricants, experts recommend that change your engine oil between 7500 to 10000 miles or after every 6 months if you’re using mineral oil (conventional oil).

If you are using synthetic oil, you can change it up to 15000 km or after 6 months to 1 year, says (Especially if you’re using new model cars or operating at the optimum conditions).

The need for oil changes also depends upon your driving condition. If you drive your car below 10 miles at a time ( which means the oil doesn’t get hot enough to boil off moisture condensation) or start your engine often, you must have to change your oil twice a year even if it would be at 1000 miles at each change. But if you are driving more than 20 miles at a time flat freely, you can follow the owner’s manual recommendation.

A bottom Line

Maintenance of engine oil is as important as of the engine itself. If you need to get maximum efficiency from your car’s engine, adding the best quality engine oil is very necessary. Every car’s owner must be aware of checking engine oil quality and should use the best quality engine oil.

In most cases, your car’s manual is the best recommendation regarding every aspect of your car maintenance including engine oil. Such as choosing its grades and changing time. However, you don’t need to always follow the recommended guidelines and set the timelines for oil changes every time. Sometimes, your car will also tell you itself when it’s time to change engine oil.

How does your car tell you that it’s time to change the oil?

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