Lubricant Choice – Getting it Right Can Save You Money

Now, more than ever, lubricants are an extremely vital component in any engine, whether petrol or diesel. The latest engine designs put a lot of stress and constraints on lubricants, and whether the vehicle is a three door hatchback, or an all out racing machine, selecting the correct grade of engine or transmission oil is vital to the efficient running of the unit.

Emissions Legislation

Emissions legislation over the last couple of years has pushed engine hardware designers to look at innovative approaches to complying with the ever tougher limits imposed upon them. Controlling levels of Nitrogen Oxides (NOx), Carbon Monoxide (CO), Particulate Matter (PM), and Hydrocarbons (HC, typically unburnt fuel) that appear from the end of the exhaust pipe, has given rise to a variety of exhaust after–treatment devices that must operate at maximum efficiency. These come in the form of catalyst devices and filter systems.

Advanced electronic management systems monitor the emissions levels every fraction of a second, and if there is a decrease in performance, they have the ability to shut the engine down or switch it to ‘limp home’ mode at reduced power. Both occurrences come at a financial cost to the owner, in the form of remedial action by dealer workshops, and the biggest reason for this decrease in efficiency of the after–treatment devices is down to poor lubricant selection.

Decomposition of Metallic Based Additive Compounds

A new term, SAPS, has slipped into the dictionary for lubricant performance. The term stands for Sulphated Ash, Phosphorous and Sulphur. These are either components of the additive system (Phosphorous and Sulphur that form part of the anti–wear compound), or from the burning of the lubricant (Sulphated Ash formed by the decomposition of metallic based additive compounds) in the combustion chambers.

These by–products find their way into the exhaust gas stream, and if their levels are too high, they will cause a reduction in performance of the after–treatment devices. Phosphorous and sulphur will poison the catalysts and sulphated ash will block filters (primarily DPFs or diesel particulate filters).

To guard against this, ACEA (a body consisting of European vehicle manufacturers) produced a set of engine oil specifications with chemical limits. These ACEA ‘C’ Categories (C1, C2 and C3) have been designed to protect, along with the engine, the sensitive after–treatment systems and keep everything working efficiently.

The choice of lubricant is critical. It is recommended to check lubricant specifications in the handbook against the product being used, in order to avoid the consequences previously outlined.

Analysing used oil samples can provide critical information about how an engine or transmission is performing. The data generated can not only enable a judgement to be made in terms of a mechanical or lubrication remedy, but can provide the owner with reassuring feedback on the performance of the vehicle.

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This page was last updated
Saturday, 29-Jan-2011

Tailored & Detailed Approach to Used Oil Analysis