A Brief History of Engines and Engine Oils for Cars

A Brief History of Engines and Engine Oils for Cars

Surely, I can just put any old oil in my car, well the answer is no!

Introduction

This technical article is split into 2 parts and in all covers some of the key developments in motor car engine designs and the various functions the engine oil must perform to ensure optimum performance.  The starting point is the 1980s and 1990s, whilst the second part looks at the developments from the new millennium and how to pick the correct engine oil.

All industries must evolve and innovate to keep pace with demand, customer needs, trends, legislation and of course environmental pressures and the passenger car world is no exception.  The internal combustion engine (ICE), petrol or diesel, has seen automotive engineers continually develop new strategies to improve efficiencies, reduce fuel consumption and lower harmful emissions. As such car engine designs have become more complex.  This means that the oils used in these automotive engines must follow suit. You cannot just use one grade of oil in all car engines.

 Part 1 engine oil usage during the 1980s and 1990s

The combustion process in today’s car engines is still the same as it was first developed, ie intake-compression-ignition-exhaust, whether petrol or diesel.  However, it is how that power is harnessed, the reduction in fuel consumption and the decrease in harmful emissions that has changed.  Maximising the potential of that power has led to refinements not only in fuel delivery systems, combustion chamber and piston designs, but also in the materials used in engine and component construction as well as the adoption of advanced electronics, sensors and engine management systems. These designs have helped to improve fuel efficiencies and legislation has pushed for the reduction in emissions. Simply put, engines today are rather complex pieces of equipment.

Engine Evolution - the 1980s to 1990s

During this period of engine evolution, it felt like the major engine developments were based on the need to go faster! Do you remember all those cars with turbo decals, multi-valve badges and more “umph” when you put your foot down?

 Turbo, Multi-valve and Catalytic technologies

At whatever period of innovation, we’re looking at, car engine oil technology has been fine-tuned to offer the correct levels of protection as demanded by the Original Equipment Manufacturers (OEMs).  The introduction of multi-valve designs (2 inlet/2 exhaust), variable-valve lift technology and turbocharging, led to increased power and more demands on the engine oil.  In these engines, the oil has to have additional anti-wear chemistry to look after camshafts, particularly the cam lobes and improved detergency to keep components clean, such as valve guides and valve stems.

Turbocharging also pushes the job the car engine oil has to do even further. The engine oil is subjected to high temperatures and improved detergency is required to keep the turbo bearing clean and free of deposits.  If the oil did not achieve this the bearing would fail and the turbocharger would need to be replaced. 

Three-way catalytic converters became mandatory to help control emissions, but these were sensitive to engine lubricant chemistry and formulation.  Too much sulphur or phosphorous in the exhaust gases would poison the catalyst and affect the emissions and therefore the engine oil has a part in controlling these emissions. 

Some automotive OEMs had problems with the formation of sludges, excessive camshaft wear and piston deposits.  Their OEM specifications were adapted to ensure any of these operational issues were combated by the engine oil.

The 1990s to the year 2000

During the 1990s, emissions legislation began to force changes in how the automotive OEMs designed their engine platforms and exhaust systems. More power, but without the harmful emissions was the key objective.  Over the next 30 years, innovations were driven by the need to clean up exhaust gases and drive down the level of atmospheric pollutants.

 Common Rail Diesel Fuel Injection

The evolution of the internal combustion engine used in the automotive sector continued. Indirect diesel fuel injection was replaced with common rail injection.  This provided a much more accurate metering of fuel that matched demand and with a greater level of atomisation, due to substantially higher injection pressures, fuel efficiency was vastly improved. This heralded the generation of quieter diesel engines. However, these higher injection pressures can wash away the protective oil film from the bores (as the fuel is directed straight in).  The engine oil needs to be enhanced and required the addition of higher levels of antiwear performance to protect the liner and piston rings in these types of engines.

 Exhaust Gas Recirculation

Exhaust gas recirculation (EGR) was introduced to help control the level of NOx emissions.  However, because of the higher level of soot generated, using this method, additional lubricant performance was required. With EGR, by the introduction of ‘spent’ exhaust gases back into the fuel/air mixture, you are essentially starving the combustion process of oxygen so that the nitrogen doesn’t become oxidised to nitrogen oxides (NOx).  This also results in incomplete combustion and rather than carbon being oxidised to carbon monoxide/dioxide, it is present as soot.  Soot is abrasive, causing accelerated wear and it can overly thicken the oil resulting in inadequate cooling.  Re-circulation of the exhaust gases also poses other potential issues as it is quite corrosive.  Engine oils designed for use with EGR have enhanced wear protection, good dispersancy (to keep the soot circulating freely to prevent thickening) and the ability to provide an effective oil film as a barrier to corrosion.

Selective Catalytic Reduction (Adblue®)

In addition to EGR, Selective Catalytic Reduction (SCR) was introduced, better known as Adblue®.  Like EGR, this is a NOx reduction process that uses a solution of urea, sprayed into the exhaust gas stream. A chemical conversion takes place between ammonia (in the urea solution) and NOx gases in the exhaust stream to produce nitrogen and water vapour. In other words, two harmful chemicals are converted to two harmless chemicals, which then pass into the atmosphere without causing detrimental side effects. This reaction takes place in a catalyst fitted to the exhaust system.  The catalyst can become ‘poisoned’ as it is sensitive to sulphur and phosphorous that originates for the engine oil formulation.  This occurs because a small amount of oil is burnt when compression rings, valves and valve guides are lubricated.  The engine oil formulation must be balanced to provide enough chemistry for component protection but not too much that the catalyst becomes prematurely poisoned and ineffective.  If it does, the engine management system may shut the engine down or provide a limited amount of power (limp mode) to get the vehicle to a workshop for remedial action.

The evolution of car engine design did not stop after the 1990s. The desire to develop more reliable engines with increased fuel efficacy and lower emissions continued and this is explored in detail in part 2 of this technical article.

Written by Adrian Hill, Morris Lubricants Technology Manager
 

Disclaimer.  The above is a generalised timeline of the widespread adoption of these technologies there are exceptions that do exist.