Hero background image

Lubricant Fundamentals

Engine oil is the lifeblood of an internal combustion engine, without a good supply of quality oil an engine will destroy itself in seconds


The engine oil’s primary job is to lubricate the moving parts. It does this by forming a thin film over the machined surfaces of the engine’s components to prevent them from actually touching each other, and therefore causing friction, wear and damage.

Lubricants however do more than lubricate – they prevent corrosion, take heat away from the combustion chambers aiding the cooling system, and remove any potentially damaging dirt particles from the engine by transmitting them to the oil filter. As the engine oil reduces the friction between engine components, it also affects the fuel economy and even improve the engine’s power output if the correct oil is used.

One of the most important aspects in manufacturing reputable lubricants, is the quality of the raw materials that you start with. The “ingredients” that we use are second to none, which is why our products meet the latest and highest Original Equipment Manufacturers approved requirements. They are designed to advance both the performance of the machinery as well as reduce the emissions, maintenance, and wear and tear of the working parts. Driving further efficiencies in fuel economy our technical teams work hard in their laboratories to ensure the latest technologies maximise results whatever the application.


Oil additives are chemical compounds that improve the lubricant performance of base oil (or oil 'base stock').

Additives have three basic roles:

  • Enhance existing base oil properties with antioxidants, corrosion inhibitors, anti-foam agents and demulsifying agents.
  • Suppress undesirable base oil properties with pour-point depressants and viscosity index (VI) improvers.
  • Impart new properties to base oils with extreme pressure (EP) additives, detergents, metal deactivators and tackiness agents.

Additives come in a wide and varied selection, but all have one common objective, to enhance certain desirable characteristics in a fluid and reduce to impact of the undesirable characteristics. Some of the most common are listed below together with their primary purpose within the finished lubricant.

VISCOSITY MODIFIERS - Allow the lubricant to cover and maintain a viscosity range that would not be possible otherwise.

DISPERSANTS - Prevent soot and other combustion by products and contaminants congealing and creating sludges.

DETERGENTS - Ensure that carbon deposits and varnishes cannot form and keep internal components clean.

BN BOOSTER - BN refers to Base Number which is effectively the ability of the lubricant to neutralise acidic compound created by the fuel combustion process.

ANTI-OXIDANTS - As the name suggests these help the lubricant resist oxidation.

PPD (POUR POINT DEPRESSANTS) - These help the lubricant operate at a lower temperature than it could otherwise, the “pour point” of a lubricant is exactly that, the point at which the lubricant ceases to pour.

ANTI-FOAM - Foam can lead to excessive oxidation; these additives help drastically reduce its formation.


Friction is a force between two surfaces that are sliding, or trying to slide, across each other. Friction always works in opposition, resisting the direction in which the object is moving. Friction produces heat and always slows a moving object down; brakes are an excellent example. The objective of a lubricant is to control or, as much as possible eliminate this friction, thereby allowing the surfaces to slide whilst also dissipating heat.

Mineral, Synthetic and Semi-Synthetic Oils

MINERAL OILS is oil that came out of the ground and has then been refined to make it suitable for use in vehicles. During the refning and processing, impurities are removed. Mineral oils are ideal for older vehicles that were developed to run on less technologically advanced lubricants, which can actually have adverse effects on older gaskets and seals.

SYNTHETIC OILS are man-made,and designed with specific properties to meet the exact demands of modern engines and conditions. This makes them more expensive to produce due to a more complex manufacturing process, but because they are tailor-made they provide the best performance, protection and fuel economy. They also remain stable at very high temperatures and fluid at very low temperatures.

SEMI-SYNTHETIC OILS are a blend of mineral and synthetic oils. They provide better performance, protection and fuel economy than mineral oils, but not as good as a full synthetic. Most cars on the road today will use at least semi-synthetic oil, with more modern engines designed to make use of fully-synthetic oils and technology.

All oil types are not suited to all engines. So before choosing between standard mineral oil, semi-synthetic oil or synthetic oil, it is important to follow your vehicle manufacturer’s recommendations. Please contact us to check which oil is right for your vehicle or machinery or click here for our online lubricant finder.

Monograde Oils

Monograde oils are, as the name again suggests, single grade lubricants. They contain no specific chemistry to allow them to span multiple viscosity grades. These types of oil are often used in classic and vintage applications that pre-date the introduction of multigrade lubricants.

Multigrade Oils

As the name suggests fluids of this type cover multiple grades so how is this possible? A fluid can only be one viscosity at any given temperature, understanding this helps better understand multigrade oils. Viscosity modifiers are the chemistry that allows a fluid to span the viscosity properties of two different grades.

Two numbers will usually appear on a label separated by a “W” meaning winter, an example would be 5W-30. So simply put the lubricant needs to be a low enough viscosity to be pumped around the engine and start protecting the internal components when cold but also ensure that at the running temperature of the engine the lubricant is viscous enough to also provide that same protection. The first number indicates the lubricants cold temperature viscosity characteristics, the second its operating temperature viscosity characteristics. The viscosity is measured according to the SAE J300 standard (see below) and must meet tight limits to comply.


Standards & Specifications

Standards are important to all lubricant products. They help ensure the customer knows what they are buying and helps compare the different types of oil available. When a lubricant is given a standard it is based on a number of 'qualities and performance properties' that the lubricant possess or how they perform for things like, fuel economy, wear, soot build up, sludge and oxidisation. Different standards are used in different parts of the world and there are different standards for cars and motorbikes.

There are a number of worldwide technical organisations involved in the formulation of lubricant standards that issue, maintain and police specifications. Their job is to produce specifications that will protect and maintain the engines of the vehicle throughout its lifetime.

ACEA (EUROPEAN AUTOMOBILE MANUFACTURERS ASSOCIATION) - This body's membership includes all the major European vehicle makers, both passenger car and commercial. They are responsible, with input from the additive & base oil manufacturers for agreeing and setting the engine lubricant standards for use in their vehicles. These tests are periodically reviewed and re-published around every two years and are known as “sequences”. Lubricant blenders and suppliers are required to sign a letter of conformance allowing them to quote the ACEA specifications on labels and product information.

ACEA specifications are all prefixed with a letter and then a number, for example you may see in a vehicle handbook a phrase like “A 5W-30 viscosity grade lubricant meeting the specification ACEA A3/B4”.

The prefix A indicates that the specification is designed for gasoline engines, and the B indicates a diesel engine. Many modern engine oils are capable of meeting multiple ACEA specifications simultaneously. The number relates to the category within that class and will have different physical and chemical limits.

So ACEA A3 is for a petrol engine that requires the characteristics of a class 3, the same is true for the B4.

The ACEA classifications relate to:

  • A/B Categories, Petrol & Light Duty Diesel Engines
  • C Categories, Petrol & Light Duty Diesel Engines with Exhaust After-treatment Devices
  • E Categories, Heavy-Duty Diesel Engines.

API (AMERICAN PETROLEUM INSTITUTE) - This association produces the lubricant specifications for the US and South America. As with ACEA the major vehicle manufacturers, additive & base oil manufacturers produce lubricant specifications for this market.

API specifications are prefixed with a two letters such as API SN or API CI-4, as with the ACEA specifications the first letter denotes the type of engine, its designed for and whilst the following is not the actual meaning of the letters it sometimes helps to think “S” spark- petrol & “C” compression-diesel, to remember which relates to which.

Whilst API specifications are more common in the UK when specifying gear oils (API GL-5) they are not unknown in the handbooks of imported vehicles. Many modern lubricants can claim both ACEA & API specifications on the same product.

Both ACEA and API periodically update their specifications to keep pace with changing engine design and legislation, these updates are however handled slightly differently by each body.

ACEA issue an updated sequence containing the new chemical and physical limits but do not alter the naming convention. They also remove and add new specification in reaction to changes in engine design or legislation and the latest are the 2016 sequences, the industry then formulates to these new specifications.

SAE (SOCIETY OF AUTOMOTIVE ENGINEERS) - This association produces a huge range of standards but as far as the lubricants industry is concerned the most common is the SAE J300 & 306. These standards detail the viscosity limits for engine & gear lubricants and ensure consistency across globe.

JASO (JAPANESE AUTOMOBILE STANDARDS ORGANIZATION) - This industry organisation is responsible for setting specifications for lubricants across a broad range of Japanese hardware. JASO small engine specifications are broadly recognized and have been adopted globally by the industry as key performance standards for both 2-stroke and 4 stroke applications.

ILSAC (INTERNATIONAL LUBRICANTS STANDARDISATION AND APPROVAL COMMITTEE) - This is an organization through which Ford, General Motors, Chrysler and the Japanese Automobile Manufacturers Association, Inc. (JAMA) develop minimum performance standards for passenger car engine oils used in petrol fuelled engines. There specifications are based upon API’s but with additional performance and fuel economy requirements.

OEM (ORIGINAL EQUIPMENT MANUFACTURER) - Many manufacturers, in addition to quoting the specifications above almost always have their own lubricant specification. These are usually based upon one of the industry standards with additional or more stringent limits in some areas. It is common for a lubricant to carry both industry and OEM specifications on a single product.



The viscosity of a fluid is a measure of its resistance to flow. For liquids, it corresponds to an informal concept of 'thickness': for example, gear oil has a higher viscosity than automatic transmission fluid. As far as lubricants are concerned viscosity is reduced as temperature rises and increases as temperature reduces. Please click on the video below for more information on oil Viscosity.

This is enhanced with the use of viscosity modifiers and pour point depressants which act together to give the finished lubricant the characteristics of a 5 grade when cold but a 40 grade when at running temperature. We measure that the finished lubricant meets these physical limits by using two pieces of equipment CCS (Cold Crank Simulator) measures the 5W part and chills the sample down to -30C. Once at this temperature the viscosity is measured and must fall below a maximum viscosity specified in the SAE J300 classification. This, as the name suggests simulates the lubricants ability to flow at low temperatures when the ignition is turned on by the driver.

The tests we run tests on every batch of engine oils, depending on the product are:

  • MRV (Mini Rotary Viscosity) basically the pumpability and yield stress of a lubricant.
  • Titration which measures the lubricant ability to neutralize acidic compounds produced by fuel combustion ensuring they cannot corrode the engines internal components.
  • NOACK Volatility simulates the evaporation loss that the lubricant will be subject to during its life, to preserve the viscosity integrity.
  • HTHS (High Temp/High Shear) A measure of the lubricants resistance to flow under conditions resembling highly-loaded journal bearings inside the engine.
  • Sulphated Ash measures residual ash and the test involves subjecting a sample to 700C in a muffle oven until only ash is left. This is further processed with acid and finally weighed and must fall under a certain level. Sulphated ash levels are critical in protecting the sophisticated after treatment devices fitted to many vehicles.

ICP Analysis (Inductively Coupled Plasma) measures the elementals within the oil or its chemical footprint to ensure the limits are within specification. The test involves introducing a diluted sample of the lubricant into a torch burning at around 10,000K which instantly vaporises it. The machine can then determine from the wavelength and frequency of the emitted light the exact element and concentration.


Viscosity Index

Viscosity Index, often referred to in the lubricants world as (VI) is a number used to express how much a fluid's viscosity changes relative to temperature. The less it changes across a range of temperatures the higher the VI. Viscosity Index Improvers (VII) are extensively used within lubricant formulations to increase the VI of a fluid.

Please contact us to check which oil is right for your vehicle or machinery or click here to use our Online Lubricant Finder.