Shell’s new motor oil helps to mitigate abnormal combustion phenomenon

Shell Helix Ultra SN Plus is designed to cope with high temperatures

01 November 2018 - 14:27
Image: 123RF/Ensup

“It’s the Nineties, Bill. Downsize!” quipped Goldie Hawn in the cult classic movie The First Wives Club. That was 22 years ago, but scaling back is very much the order of the day even as we prepare to enter the third decade of the new millennium.

Most car makers seem to have embraced the concept, with even high-end brands like Aston Martin and Lamborghini now featuring more modestly sized, if not quite small, forced induction engines.

In the experience of the Ignition team, the real-world efficiency of some of these power plants leaves much to be desired. As an example, Opel claims a combined fuel consumption figure of 4.7 l/100km for the 1.0-litre turbocharged Adam, but the best we could muster during our recent test period was 8.1 l/100km. And there are other, more serious issues affecting turbocharged gasoline direct-injection (TGDI) engines.

Low-speed pre-ignition (LSPI) is an abnormal combustion phenomenon that occurs at low engine speeds, when the fuel/air mixture in the combustion chambers ignites before spark timing. LSPI can cause engine knock, broken spark plugs and cracked pistons – and, in severe cases, complete engine failure. Its exact cause remains unclear, although it is widely accepted that motor oils can play a role. Research has indicated that a drop of oil in the cylinder may combine with fuel droplets to create hot spots in the combustion chamber, which in turn prompts ignition before spark timing is intended to occur.

Just as car manufacturers adapt to trends, so do oil companies – and Shell has formulated a motor oil that contributes significantly less to LSPI. Dubbed Helix Ultra SN Plus 0W-20, this fully synthetic lubricant is significant for two reasons. First, its ability to withstand the stress and extreme temperatures generated in high-performance engines prevents oxidation of the oil. Oxidation causes the oil to thicken and reduces its ability to protect the engine.

In addition, new Helix Ultra SN Plus has been designed with Shell PurePlus Technology, a cutting-edge process that converts natural gas into a pure base oil with stronger molecular bonds and virtually none of the impurities found in crude oil.

All of which sounds impressive to a petroleum engineer, but what does it mean for the average motorist? As mentioned above, Shell’s product is designed to cope with high temperatures but its low viscosity also allows the oil to flow up to three times faster at temperatures as low as -40°C, which makes for easier starting and quicker engine warm-up.

The low viscosity also means less energy is consumed in transporting the oil to the engine components it needs to lubricate. You don’t need to be an engineer to know that less energy consumed equates to less fuel used, meaning you’ll also save at the pumps.

As Bill found out soon enough, downsizing is an ongoing process that can be uncomfortable and often costly. Small capacity, forced induction engine technology is still relatively new and some growing pains, such as LSPI, are to be expected.

The good news for motorists is that thanks to the efforts of companies like Shell and its more than 200 researchers around the globe, those growing pains don’t have to break the bank.

This article was paid for by Shell.