HSCC June 2021 issue 129 | Page 28

ADVERTORIAL : WITHAM MOTORSPORT

Understanding oil

For older engines , using the incorrect oil with possibly high levels of additives can be disastrous as most modern engine oils are not compatible with older technology and will cause significant damage .
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We asked Witham Motorsport , manufacturers of lubricants since 1921 and UK importer and specialist of Motul lubricants , to talk about oil technology .
Modern technology and additives In 1966 Motul became the first to bring a semi-synthetic multigrade oil to the market . Today modern multi-grade lubricants are made using mixtures of synthetic base oils and blended with synthetic additive technology that enhances the lubricating properties , ability to withstand extreme temperatures and extending the oil drain interval . Today an engine oil is typically made up of around 75 % to 85 % base oils and between 15 % and 25 % additive technology .
These additives are made up of anti-oxidants , anti-wear and rust prevention chemistry . In addition to these basic performance additives , modern lubricants contain detergent properties keeping the engine clean , and dispersants that stop sludge forming . There are also TBN ( total base number ) boosters that allow the lubricant to neutralise acidic compounds produced during fuel combustion .
One of the simplest examples of where additive technology enhances the properties of an engine oil , is a pourpoint depressant . As the name suggests the pour point is the temperature at which the oil ceases to flow ( pour ). A pour-point depressant will allow the lubricant to have a lower pour-point than it would have normally .
The quality and specification of an engine oil is shaped today by the quality of the raw materials and the technology that goes into it . Modern technology packages that go into oil can vastly improve fuel economy and engine performance . This chemistry must be balanced to also meet both the vehicle industry and OEM specifications .
Multigrade viscosity explained One of the most common questions asked is : “ How can a 5W-40 lubricant be both an SAE 5 grade and an SAE 40 grade ?”
Put simply , it cannot . A fluid can only be one viscosity at a time . We often see viscosities in modern engines listed as 5W / 40 . The ‘ W ’ equals winter and simply means that the oil must have a certain maximum viscosity / flow at low temperature , and the number after the W is the ‘ hot ’ viscosity rating . So , in short 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 .
This is achieved with the use of viscosity modifiers and pour point depressants which act together to give the finished lubricant the characteristics of a 5W grade when cold but a 40 grade when at running temperature .
The newly manufactured lubricant is assessed at source to ensure it meets these physical limits by using two pieces of analytical 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 by the driver .
Viscosity at 100C measures the 40 part or the grade and the lubricant is heated to 100C and then , again , its viscosity is measured and must fall between a lower and higher limit according to the same SAE J300 classification . So , the viscosity stated simply means that lubricant displays the characteristics of a 5W at -30C , but the characteristics of a 40 at 100C .
Multi-grade oils revolutionised the lubricants industry and ended the days of having separate summer grade and winter grade oils . The advances in lubricant technology have also vastly extended drain intervals .