Engine Lubricants Play a Critical Role in Reducing Passenger Car Emissions
In recent years, increasingly strict environmental regulations aimed at reducing greenhouse gas emissions have forced passenger car OEMs to make substantial modifications to engine hardware technology. In addition to continuous increases in power density, the application of highly effective emissions control systems has changed the dynamics of engine combustion. And whether leading or following changes in hardware design, the dynamics of lubrication design continue to enable advanced engine technologies and play a critical role in emissions control.
The engine lubricant supports emissions reduction in various ways. First, by decreasing internal friction, it allows the engine to run more efficiently and reduces fuel consumption. It’s second (and perhaps less known) purpose is to protect emission systems hardware — particularly, the three-way catalyst (TWC) and the diesel particulate filter (DPF). The DPF used in diesel engines, only performs to its fullest potential when the appropriate engine lubricant is used. Read more about how the right engine oil will enable these emissions control devices below.
The Three-Way Catalyst
The TWC is a honeycomb-like structure coated with platinum, palladium and/or rhodium. It is a critical part of the emissions system that works by oxidizing combustion byproducts, thereby reducing the concentration of emissions in the exhaust. The three-way catalyst is named for the three exhaust emissions it reduces — carbon monoxide, hydrocarbons (unburned gas) and nitrogen oxides (the smog-producing pollutant). When these exhaust emissions pass through the catalyst’s honeycomb shaped filter, the resulting chemical reaction converts dangerous emissions into harmless carbon dioxide, water and nitrogen.
Oil additive technology plays an important role in meeting emissions standards by extending the life of the TWC, and at the same time providing adequate wear protection for engine components. In recent years, meeting these standards has become more challenging as global regulating agencies tighten legislation to ensure OEMs prove their technologies not only perform under testing conditions in the laboratory, but also in real-world, end-user applications.
TWC poisoning is a harmful (and cumulative) condition that occurs when the catalyst is exposed to exhaust containing substances that deactivate its surface. It is the responsibility of the lubricant to reduce this condition and maintain the integrity of the TWC as the vehicle ages, particularly after it exceeds the 100,000-mile mark.
The Diesel Particulate Filter
Another critical part of the emissions systems in diesel engines is the diesel particulate filter or DPF. The DPF is an after-treatment device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine. DPFs can remove 85 — 100% of soot or exhaust particulates. But, the DPF can quickly become blocked if a lubricating engine oil with high Sulphated Ash Phosphorus and Sulphur (SAPS) is being used. Choosing an engine oil with low SAPS will reduce DPF blockage ensuring cleaner exhaust gas and maintaining vehicle efficiency. Particulate filters are mainly used on diesel engines today, but legislation may expand usage more widely to gasoline particulate filters (GPFs).
Lubrizol is focused on developing additive technology that can accommodate DPFs in new and more effective emissions systems while providing exceptional lubricant performance in the areas of wear and durability. As the demands for reducing emissions become more complex, additive technology will continue to evolve and Lubrizol is leading the way.
