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Car Care & Valeting

Engine Oil Selection

Today, over 48% of cars and light commercials on the UK’s roads require an engine or manufacturer-specific oil. That number is growing at around 5% every year, which has serious implications for anyone who gets it wrong.

Modern engine oil is a very sophisticated, highly technical product. Its primary role of reducing friction between the moving parts – by separating them with a microscopic film of lubricant – has not changed since the invention of the internal combustion engine. However, oil also plays a vital part in preserving the integrity of seals, cleaning and inhibiting corrosion of components and dispersing around a third of the heat generated by the combustion process from the engine.

In fact, by harnessing the transformative power of chemistry, motor oil has come a long way in a relatively short time. Early developments leading to the formulation of synthetic oils were originally driven by the aviation industry after World War II. By the 1970s synthetic oils really took off in the automotive field and gradually began to replace traditional mineral oils.

The process was given added impetus when the European Automobile Manufacturers Association (ACEA) established its first service-fill oil ‘sequences’ in 1996. Based on a series of demanding engine tests, the sequences are a benchmark set of lubricant standards. They are classified by their suitability for gasoline and diesel passenger vehicle engines, now harmonised as the ACEA ‘A/B’ sequences. The increasingly relevant ACEA ‘C’ class of low SAP oils are intended for vehicles fitted with three-way catalytic converters (CATs) and diesel particulates filters (DPFs).

The ACEA classes are sub-divided into categories, e.g. A3/B3 etc, indicating oils for different applications within a class and, since their introduction, have been upgraded on average every two years. This has kept the sequences abreast of new engine design and manufacturing technologies, hugely extended oil change intervals, the never-ending demand for greater power, improved fuel efficiency and, in particular, stricter EU legislation to reduce exhaust emissions and the disposal of waste oil.

By the end of the 20th century, vehicle manufacturers began introducing engine-specific oil formulations for their own models and giving them special codes – VW-this, MB-that, BMW-the other and so on. This resulted in a huge proliferation of products necessary to meet all requirements in the market, especially when the VMs later upped the ante by making the use of these oils a warranty-critical requirement in servicing regimes. Thus the business of engine oil application became more focused and more complex. The common practice of fitting a ‘one-size-fits-all’ 10W-40 in almost any vehicle that passed through workshops has since gone into rapid decline.

According to BTN Turbo, over 90% of turbo failures are oil related, so consider how much it might cost to replace a turbocharger that has failed due to the wrong oil being used. Furthermore, what about the CAT that has been irreversibly ‘poisoned’? Or the DPF that has been terminally blocked, all because the appropriate ACEA ‘C’ category oil had not been used? Such errors can result in hefty bills, typically into 4 figures.

Fortunately, product selection is being made easy: Comma’s online, VRM-based application data at www.commaoil.com is constantly updated, making the identification process as simple as possible. Even better, every recommended application is backed by Comma’s 100% quality guarantee,which features prominently on the unique vehicle-specific product report that can be printed out and handed to your garage customer with their invoice.

Where is the motor oils market heading?

Oil change service intervals continue to get longer, with 40,000 miles for advanced diesel engines anticipated in the future. At the same time, average sump capacities are now below 5 litres, a reduction of 15–20% in little more than the last decade. Industry forecasters say this will inevitably flatten and may even shrink the market in terms of oil volumes, but this will be more than compensated by its growth in value as a result of the premium price commanded by the latest lubricants. “In our market, everything is driven by what the vehicle manufacturers demand. Meeting those demands results in products which carry a very good margin for everyone in the distribution and fitting chain,” says Comma Sales & Marketing Director, Mike Bewsey.

He adds that it is also important for distributors to recognise the value and respond to the growing demand for engine-specific top-up oil in 1 and 2 litre packs. “Extended oil change intervals mean that this slice of the market offers attractive on-going profit opportunities, because all conventional engines consume some oil by design. Topping up with the correct, matching oil is as warranty-critical as filling with the right product in the first place. Comma is heavily engaged in educating motor factors, retailers and workshops on this issue and encouraging them to include top-up in their service offer. As workshops grasp the opportunity, it makes sense for distributors to stock ‘shadow’ their sales of manufacturer-specific 5 litre and 20 litre products with proportionate stocks of their top-up equivalents.”

Why does oil contamination damage turbos?

As turbochargers can operate at over 240,000rpm and endure temperatures of 950°C, turbo bearings are under great stress. The turbine shaft and bearings rotate in a thin film of oil. Consequently, any fault with the oil supply to the turbo means its bearings are likely to fail before the engine’s main bearings. Running a turbo without oil for five seconds is as harmful as running an engine without oil for five minutes.

While it is important to ensure that the engine oil pressure meets the manufacturer’s specifications, it is even more critical that the oil feed pipes to the turbo are clean and clear, so you are certain they can supply uncontaminated oil, at the correct pressure. Contaminated or dirty oil will scratch or score the bearings, leading to rapid wear and ultimately, turbocharger failure.

What causes contaminated oil?

• Blocked, damaged or poor quality oil filters

• Carbon build-up in the engine – this can rapidly contaminate even new oil

• Accidental contamination of new oil during servicing

• Malfunctioning oil filter bypass valves

• Engine wear – leaves swarf deposits in the oil

• Oil that has degraded due to excessive temperatures or extended service intervals

Preventing turbo failure caused by contaminated oil

• Always use fresh oil and new oil filters as recommended by the engine manufacturer when fitting a new turbo

• Ensure the oil is the correct grade for the engine

• Clean or replace oil inlet pipes to eliminate any carbon deposits or sludge that could enter the turbo or restrict oil flow to the bearings

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