Most diesel enthusiasts know the 15W-40 oil they’ve traditionally put in their engines is thicker and has more viscosity than the 10W-30 or 5W-40 gasoline engines use. Fewer diesel fans have a complete grasp on the other symbols and numbers found on a bottle of oil.
First off, API stands for American Petroleum Institute, which was created during World War I to facilitate the United States’ war efforts. Today, this trade association of more than 400 corporate members has a mission to influence public policy in support of a strong, viable, international oil and gas industry. API also helps facilitate research and standards. Its Engine Oil Licensing and Certification System (EOLCS) is a voluntary licensing and certification program that authorizes engine oil makers to use the API symbol of approval. Back in 2006, you might remember when the CJ-4 category of diesel engine oils came online. The Engine Manufacturers Association (EMA) requested this oil category because they needed it for new emissions equipment such as EGR systems and exhaust aftertreatments. Today, a new oil standard is being worked out, and we take this as a harbinger of the engine changes to come. By looking at how the oil will be changed to fit the new standards, we’ll be able to deduce what future engine schemes might be.
The full synthetic Shell Rotella T6 5W-40 engine oil is said to deliver fuel economy impro
PC-11: A Category Designed for New Engine Technologies
PC-11 is a new diesel engine oil category currently under development that will be ready in 2016. The Engine Manufacturers Association (EMA) says they need a new oil category because of the changes in engine technology designed to meet emissions reduction, renewable fuel introduction, and fuel economy standards. PC-11 oil will need to have improved:
Oxidation stability: Just like rust that attacks the outside of your truck, oxygen reactions are breaking down your oil and are taking place inside your diesel. If oil oxidizes too much, an acid is formed, which can cause engine corrosion. If it goes too far, the size of the oil molecules increases and since this is what determines viscosity, plugged oil filters and damage to areas with tight tolerances can occur. PC-11 enables greater biodiesel fuel compatibility and allows for higher engine oil temperatures (since oxidation increases with increased temperatures). The EMA is calling for engine oil temperatures to be 10 degrees hotter.
Aeration: This condition is what happens when air bubbles or foam form in the oil and is often caused by incorrect oil level. Too low and the sump will suck air with the oil, too high and the crankshaft will churn the oil in the sump into a froth. The other factor that puts air into the oil is engine speed. The bubbles associated with oil aeration can cause oil blockage to lash adjusters, journal bearings, and connecting rod bearings. It can also cause oil pump cavitation. Aeration can also cause horsepower losses and increased engine temperatures since the oil can no longer carry off as much heat. When these bubbles pop, a flammable gas is produced that can ignite and further increase engine temperatures. We can conclude future diesel engines will probably spin faster—that is why they need oil less susceptible to aeration.
Shell told us that while coolant color is a helpful guide, it’s important to not mix coola
Shear stability, scuffing, and adhesive wear protection: If you take two flat pieces of steel, cover them with oil, and then stick them together and try to pull them apart, you’ll feel a force that tries to hold them together. This thin layer of oil is also what keeps engine parts from wearing each other down. If enough pressure is added, the oil shears, which means all the molecules get lined up and the protective layer is broken down. Adhesive wear indicates one engine part rubbed another and got hot enough to weld some of its material to the other piece. The EMA asked for an oil more resistant to high-pressure forces. This makes it sound like future engines will be worked harder.
Data that supports performance increases: The final oil qualification the EMA asked for was data showing lower viscosity engine oils would be able to deliver the fuel economy benefits while not giving up any protection qualities compared to the traditional, thicker oils.
Will Heavy Trucking Go LNG Instead of Diesel Fuel?
Shell is considered an energy company right now, but before this it was an oil company. Shell says it can handle more gas than oil. Liquefied Natural Gas (LNG) is created by cooling CH4 gas to -256 degrees; in this form it becomes a liquid 600 times more energy dense than it was in its gas form. Still, you’d need twice as big a tank of LNG to get the same mileage from a tank of diesel fuel. With all the fracking going on in this country and around the world, new energy sources are being extracted. Shipping LNG in liquid form is easier to transport compared to pipelines. Shell is going all in with its investments in LNG technology, so it’s definitely possible truck drivers will be gassing up instead of fueling up in the upcoming years.
Truck & Engine Manufacturers Association
American Petroleum Institute
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