Engine oil specifications: what's the best oil for your car?


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Understanding engine oil specifications is necessary to ensure that you don't damage your car with contaminated oil. Find out more important information how to choose the right oil for your car here!

Do you actually read the content on a car oil bottle? Surprisingly, many people don’t bother to take a second look at it. This is wrong. Depending on what you have been told about the oil isn’t enough. To enjoy maximum benefits of it, you need to understand its components and how to use it.

In the scope of this post, we will provide you with almost every essential thing about car engine oil, so you can be confident choosing and changing oil for your car next time.

1. Standard engine oil components & its usage

Engine oil, motor oil or engine lubricant is a general term for numerous substances which help the internal combustion engines operate smoothly. In other words, this lubricating oil reduces friction and wear on machine's moving parts and wipe off the sludge in engines.

Standard engine oil consists of base oils, additives (detergents, antiwear additives), dispersants, and viscosity index improvers (applied for multi-grade oils). Moreover, the majority of oils are added oxidation and corrosion inhibitors.


The pie chart illustrates the distribution of engine oil components

2. Differences of Engine oil, Gear oil, Transmission oil & Hydraulic oil

As we mentioned before, engine oil or motor oil is used for internal combustion engines to reduce friction and wear in the moving parts. Oil viscosity index improvers are added to multi-grade oils only and the viscosity level varies.

Gear oil is another type of lubricants made for transmissions, differentials and transfer cases in cars. These substances are usually high in viscosity level and often contain extreme pressure additives (EP) and antiwear additives.

Transmission oil, or Automatic transmission fluid (ATF) to be more exact, is created for self-shifting vehicles. ATF is the combination of various additives to improve lubricating qualities of automatic transmission, such as antiwear additives, detergents, rust/ corrosion inhibitors, dispersants and surfactants, viscosity index improvers and modifiers, anti-foam and anti-oxidation, seal swell additives, cold-flow improvers, gasket conditioners, high-temperature thickeners, pour point depressant and finally petroleum dye.

Hydraulic oil is a special fluid based on mineral oil or water. Hydraulic fluid not only serves as a lubricant, it is also the medium to transfer and control power in hydraulic machinery (eg: excavators, transmissions, hydraulic brakes, garbage trucks, lifts or aircraft flight control systems).


Hydraulic oil color change after a period time of use

3. Engine oil specifications

Every good product goes through certain certifications before they are approved for us. Car oils are no exception. Check carefully that the oil has been certified to meet certain specifications. A good oil should have ACEA and API ratings as these are the acceptable standard.

3.1. API specs

API stands for American Petroleum Institute while ACEA stands for Association des Constructeurs Europeens d’Automobiles.

API is very basic and easy to understand. It has two different categories for passengers. S = Petrol and C = Diesel. Most oils have both diesel (C) and petrol (S) specifications. Let’s take a look at the updates of the oil specifications!

API spec Year of introduction Interpretation
SG 1989 contains a high degree of functional dispersants that are resistant to black sludge
SH 1993 has similar engine tests as SG but contains phosphorus limit 0.12% in addition to volatility, foam control and stability
SJ 1996 Its engine test is the same as SG/SH, but it contains a phosphorus limit of 0.10% as well as volatility limit variations.
SL 2001 This is mostly found in all new engine tests of modern day engines designed to align with the latest emission standards.
SM 2004 It has advanced features such as oxidation resistance, wear protection, low performance temperature and deposit protection in comparison to the older categories.
CD 1995 represents the international turbo oil engine standard for many years. It makes use of a single cylinder for engine testing.
CE 1984 indicates an improved regulation of oil consumption as well as piston deposit and wears, oil thickening, and makes use of multi cylinder engines for testing.
CF4 1990 shows continuous improvements in controlling oil consumption and deposit of pistons. It also makes use of emission test engines that are low.
CF 1994 It’s the advanced CD version. It’s mainly used for indirect injection engines.
CF2 1994 It’s the yardstick for defining accurate control of deposits in the cylinder and scuffing of the ring face.
CG4 1994 Development of CF4 made way for continuous control of oxidation stability, piston deposits and soot entrainment.
CH4 1998 Development of CG4 for better performance, is the result of more comprehensive engine tests involving either low or high-sulphur fuels.
CI4 2002 conforms to 2004 emission standards, optional to systems with up to 0.5%-sulphur fuel or when CE, CD, CG4, CF4 or CH4 is required.


Here is an example of API specs on engine oil product!

Specifications in use before the SL are no longer efficient. As a matter of fact, they have gone into extinction. For other specs apart from CH4 are still useful in older vehicles that are over 10 years old, their performance level and protection are nothing compared to the more recent specifications. In brief, the best oil specs are the most modern ones: SM, SL, CI4 or CH4.

3.2. ACEA specs

The ACEA is the European version of API in the US. It lays more emphasis on the specific oil performance. A = Petrol, B = Diesel and C = Catalyst Compatible or low Sulphated Ash, Phosphorus and Sulphur (SAPS).

Performance categories of the ACEA include:

ACEA spec Interpretation
A1 Economy petrol of fuel
A2 Performance level (standard)
A3 High performance
A4 Put aside for future use in some direct injection engines
A5 Uses both A1 fuel economy in addition to performance of A3
B1 Diesel fuel economy
B2 Performance level (standard)
B3 High performance
B4 Used on cars with direct diesel injections
B5 Uses fuel economy of B1 with performance of both B3 and B4
C1-04 Based on A5/B5-04 low SAPS, petrol & light duty diesel engine, 2-way catalyst compatible
C2-04 Based on A5/B5-04 mid SAPS, petrol & light duty diesel engine, 2-way catalyst compatible
C3-04 Based on A5/B5-04 mid SAPS, petrol & light duty diesel engine, 2-way catalyst compatible, higher HTHS, resulting in better performance

Regarding ACEA specs, car oils with A3/B3, A5/B5 or C3 index are of higher general quality compared to the rest of above list.


Normally you can find oil specs at the back of the oil bottle

3.3. Other specs to look for on car oil bottle

  • Intended use

There are various car oils on the market. Each of them serves a unique purpose. You don’t just pick any oil and use it on your car without knowing if it’s suitable for that purpose. Doing that will worsen the situation, leaving you with more problems instead of a solution. Read what the oil is intended for, thoroughly, before taking it close to your car.

  • Oil Viscosity or simply the oil "thickness"

Single-grade engine oil is labeled one in 11 grades: 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50 and 60. The "W" symbol refers to "winter", meaning the dynamic viscosity of certain oil is measured at different ranges of cold weather. The lower the grade is, the lower temperature the oil passes. Non-winter lablel oil is measured at exactly 100 °C.

A good number of modern oils put up for sale are known as “Multi-grades.” This simply means that such oils belong to two different grades of oil, and noted in the form of 20W - 30. The concept of multigrading came into use about 50 years ago to stop car users from using different kinds of oils at different seasons.

  • OEM approvals and codes

OEM approvals and codes are important variables to look out for. If they are missing, the product is most likely not certified. Using such a product is at your own risk.

You will find several OEM’s on the bottle of oils. The most commonly used ones in the UK include BMW, VW or MB. But don’t assume that any oil that has them is authentic. Although recognized companies producing oils send their oils to OEMs to get the recommended approvals, some older specs can be created with cheap materials. Be on the look out for newer specifications as they are better by all standards.

4. Types of oil for car engine

4.1. Synthetic oil vs regular oil

First, regular oil or conventional oil is refined from crude oil, remaining as the most natural oil on the market.

Synthetic oil is created from chemical compounds (base oil, powder additives and a carrier oil) to mimic natural oils but can meet extra requirements of several types of modern vehicles.

How to change oil correctly?

Actually, both these two types are made from refined crude oil but the difference lies in the refinement level. You may prefer "regular oil" because it sounds more natural and economical. However, when it comes to cleanliness and performance, synthetic oil proves higher scores because it's intentially made for engineering purposes with more added functional chemicals.

4.2. Gasoline oil vs diesel oil

To distinguish these types of oil is simple. They are used for different types of engines: gasoline and diesel.

We can't compare which is better in this case as it depends much on the engine and how you take care of it. To know the oil performing best on each type of engine, please look back the API and ACEA specifications above, remember the recommended specs and find them on the car oil bottle.

>>> Better understanding your car, more saving the maintenance budget!

5. What is the best oil for car engine?

There are many factors you need to consider in choosing the best oil for car engine. If you read thoroughly earlier parts, you can withdraw some basic lessons to find a suitable car oil bottle.

First, synthetic oil is considered better than conventional oil in many cases. It helps keep your engines cleaner, perform better and harder to break.

Second, oil products with certain API and ACEA specs have higher performance, conforming to modern vehicle standards, namely SM, SL, CI4 or CH4 (for API) and A3/B3, A5/B5 or C3 (for ACEA).

Steps to pick the right oil for your car:

1. Study the suggested oil weight and viscosity in your vehicle manual

2. Look for recommended oil type or even oil brand for your vehicle in the manual (if have)

3. Identify API or ACEA specs that suit your vehicle

4. Find the oil product with OEM codes and all above index/ specs.


More and more oil products are being introduced to the market

Popular engine oil price in Nigeria

  • Mobil oil & 5W30 engine oil

Mobil oil first appeared on the market in 1974 and now a leading brand of synthetic oil and other lubricants for automobiles. 5w30 engine oil is a successful product from this manufacturer, which is prefered by many Nigerian drivers. Prices of Mobil Oil in Nigeria vary greatly, based on the type of products and where you buy them. Below are just our collected prices from reliable sources:

Mobil oil product Price updated 2019
Mobil 1 0W-20/ 5W-30  Synthetic/ Full Synthetic 1L ₦4,410
Mobil 1 Ful Synthetic 5L ₦18,000 - ₦19,450
USA Made Mobil 1 Full Synthetic 5L ₦21,530 - ₦23,100
Mobil 1 Annual Protection Ultimate Full Synthetic 5L ₦33,600
  • Total engine oil

Total ranks number 5 in the largest international oil companies in the world, offer a vast range of products and services, including engine lubricants. Following are their product prices in Nigeria for your reference. The price may differ in certain situations due to sudden price rise, distributor's private price scheme or some other factors.

Total oil product Price updated 2019
Total Quartz 1L ₦3,500
Total 5W-30 Full Synthetic 5L ₦14,500 - ₦25,000
Total Quartz 9000 Energy OW-30/ 5W-40 5L ₦20,500 - ₦21,000

6. When does your car need an oil change?

Naijauto has once explained this thoroughly in our previous post How often should you have an oil change for your car! Just click on the link and you'll find other helpful information there.

Basically, for vehicles of the old time, changing oil after every 3,000 miles or 3 months are often recommended, but that rule is no longer true to modern vehicles. Each car has their own span of changing engine oil and you have to refer to its product manual. If you lost the manual, you could find info on manufacturer's websites or many auto forums online.

And when changing the car oil, please take note of these rules:

  • Replace the drain plug washer
  • Use appropriate oil
  • Apply lubricants to the filter seal as well

Consequences of not following rules in changing oil are serious, you can check details on the link we provide.

7. Conclusion

As obtainable with most things life has to offer, the higher the quality, the costlier it is. If you don’t want to spend good money on car oils, you’ll end up buying the substandard ones. Car engine oil made with good ingredients is often on the high side because of their quality. At Naijauto.com, we advise that you always go for the best oil for your car. That way, you get to enjoy your money’s worth, saving yourself from unnecessary car troubles. And more importantly, always maintain your car in the proper way for long-term benefits!

Chris Odogwu




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