Auto Service World
Feature   May 1, 2008   by Philippe Gauthier

Constant research has fundamentally changed the nature of traditional motor, diesel oil

Motor oil is so familiar that one easily forgets it is a fairly sophisticated item. For many people, the biggest challenge is making the switch from the traditional 10W30 oil to the newer 5W20. But do...


Motor oil is so familiar that one easily forgets it is a fairly sophisticated item. For many people, the biggest challenge is making the switch from the traditional 10W30 oil to the newer 5W20. But do they know how different those two motor oil are, and what it means for their car’s engine and its life?

In the motor oil industry, the real secret of what makes one particular motor oil different from another lies in the additives used. For example, while 10W30 oil has been known for more than 30 years, today’s 10W30 is a very different product from what it was back then.

Francis Boss, technical director at Total Lubricants, remembers that “A few years ago, oil standards were modified every four to eight years. Nowadays, they are revised every two to three years.”

These frequent changes to the additives and their proportions and mixtures all have one goal in mind: to both improve engine protection and performance, and to reduce harmful by-products in the oil which can cause damage to other components in a vehicle. For example, new standards now ask for a reduction of the proportion of phosphorous contained in motor oils. This phosphorous was contained mostly in ZDPT, a multi-function additive which was quite cheap to produce, and which was used in large doses in earlier blends of motor oils. Why is this important? Phosphorous is noxious to catalysers as it decreases their useful life. Nowadays, ZDPT constitutes no more than 0.5 per cent in volume of motor oil, and it will disappear in the near future. Due to this, catalysers made in 2008 contain 15 per cent less platinum than the previous models.

Less and less viscous oil

“5W20 oil can no longer be termed as a strange animal,” explains Francis Boss. “It doesn’t have anything to prove any more, as it has been adopted by Ford and Mazda. Others will follow. The gain in fuel efficiency is around two per cent, which is not negligible, and the problems of wear predicted by a few have never appeared.”

In fact the 10W30 standard became the rule at a time when engine building tolerances were far greater. Today, high viscosity is no longer necessary. In the next two to three years, 5W20 will become the grade of choice for North- American cars, as the new standard on oil (PC-12) will be enforced.

The next real challenge will come on the diesel side. As 10w30 becomes outmoded in cars, the highly viscous 15W40 won’t be needed any more by the trucking industry. But the industry needs to be convinced of that fact.

In Europe, most trucks travel on 10W40, and it represents a one to three per cent decrease in their fuel consumption, when compared to trucks using 15W40. Also, no increase in engine wear has ever been reported.

“In our region, people are only beginning to think lighter oil might be useful, as it ensures easier starts during cold winters,” states Boss. “It would be very useful indeed, as 50 per cent of all engine wear occurs on starts, when the oil is too cold to circulate well.”

A few years ago, Tribospec were able to demonstrate that Delo 400 oil could be changed every 60,000 km, instead of 25,000 km. Today, Total Lubricants’, Rubiatir 7900 10W30 oil can reduce fuel consumption by one to three per cent.

Emissions management in diesel engines

In newer diesel engines, the oil captures all unburned particles which once went into the atmosphere and concentrates them into the oil filter. This means modern oils have to face new kinds of difficulties, notably high amounts of carbon particles which are very abrasive. This occurs because exhaust gases are recycled into the engine before being sent outside. Two available technologies can be used to clean exhaust gases. In the European system, a little quantity of ammonium is injected. This chemical treatment is highly effective to reduce the emission of polluting gases. In North America, instead of a chemical treatment the industry relies on the particulate filter. This kind of filter can break big toxic molecules into less noxious components. Sulphurous gases are trans- formed into sulphate, which is a stable salt and nitrous gases are transformed into nitrogen and water.

This new technology reduces the amount of pollutants being endured by the oil. This is why newer diesel oils tend to contain less dispersing agents and fewer additives. For some time, people feared that these new diesel oils would be harmful to older diesel engines.

According to Jean Labont, technical advisor in Quebec of Irving Lubricants, older trucks can handle the new oil and many suppliers have already removed old-style oil from their catalogues. As the demand for it is declining rapidly, Irving thinks they might follow suit before the end of the year.

Michel Murphy a tribology (lubrication) expert with the Society of Tribologists and Lubrication Engineers based in Chicago thinks time will bring about rapid changes.

“In about two or three years, new classes of motor oil will be developed to comply with low-emission diesels,” he insists. “Oil won’t be universal any more. One type of oil will not fit all kinds of uses”

Does better durability mean the end of the regular oil change?

In Europe, an oil change is recommended at 10,000 km and up to 20,000 km for some vehicles. The same vehicle here in North America will have an oil change mandated at 5,000 km, while oil quality is the same or about the same. Why the huge difference?

Francis Boss admits frequent oil changes bring appreciable income to the independent service provider industry, but he is less certain about the need to abandon the traditional 5,000 km oil change.

“European synthetic oil is still better than our mineral oil,” he says. “Our oil filters are not designed to handle 10,000 km oil changes. They would tend to clog.”

When other experts were asked at what intervals they made their own oil changes, many said they do it at 5,000 km. Jean Labont, for one, does his oil changes at 10,000 km to 12,000 km. Francis Boss, who never waits longer than 7,000 km to take his car in for an oil change. Michel Murphy, however, proposes a 10,000 km interval, which could be pushed to 15,000 or even 20,000 km, but only under certain conditions.

First of all, you have to drive on clean roads. Avoid stop-and-go driving and quick accelerations, especially in winter when the engine is cold. A very cold winter can reduce the useful life of oil by at least 20 per cent. Driving frequently on dirt roads will contaminate the oil with dust particles and can shorten the oil’s useful life by 50 per cent. But, driving in optimum conditions with a high-quality oil, the oil can be changed every 20,000 km without doing any harm to the engine, he suggests.

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Oil-based trends

Michael Paul, manager for Eastern Canada at Valvoline, the rapid aging of vehicles used in Quebec is good news for maintenance specialists.

“In Quebec, eight out of every 10 cars have more than 100,000 km on the odometer. A few years ago, we launched the Maxlife line of oils for these cars and it was a huge success,” he says. On the diesel front, Valvoline has an advantage because of their international association with Cummins. The have developed a fully-synthetic 5W40 for extreme conditions, and it works admirably well in buses fleets.

“No more need to plug the engine in winter. That is a real revolution if there ever was one,” he adds. Synthetic oils are winning a slow-growing part of the market in Quebec. Nowadays, it sits at around five or six per cent, but it increases by about one per cent every year. We still have a long way to go if we want to reach the 30 per cent currently sold on the European markets.