Automotive Lubricants

Different Engine Oils for Different Fuel Choices


Different Engine Oils for Different Fuel Choices
© CCD Studio lianez


In my February column “How Many Years Do Quick Lubes Have Left?” I talked about the coming electric storm in vehicles. The wave of the future in mobile transportation is most certainly electric. It is a tsunami that is growing in the Far East, especially China. It is rolling across the Pacific and will overwhelm North America.

The wave is moving slowly because there are a lot (about 300 million) of internal combustion engines in the way, and they are still powering vehicles successfully and economically. Over the next 30-40 years these will be replaced by electricity-powered light trucks (pickups and SUVs) and cars.

The passenger cars, pickups and SUVs could adapt to a number of different fuels. Open-wheel race cars have run on several different fuels, including gasoline (not for long due to hazards), methanol and ethanol. If something else comes along that seems to have public and legal interest, the competition automobiles will run on that as well.

As vehicles go from personal to business, power requirements go up. According to Gill Pratt, CEO of the Toyota Research Institute, a Class 8 battery electric truck will require a one-megawatt battery, and that battery will require a one-megawatt charging station and take one hour to recharge. That’s sure to cause a major logjam at truck stops, since the U.S. Department of Transportation says there are over 150 million trucks in operation in the country. 

At this point, I’m sure many of you are still thinking that EVs are the way to go. Sure, it’s going to take time—and money—to finish the conversion, but it’s for the best. However, you know better than that. At the technological level there are still significant hurdles yet to overcome. “If you’re pulling 10,000+ pounds, an electric truck is not the right solution,” said Ford CEO Jim Farley. Not so coincidentally, he also noted that 95% of Ford’s F-250 Superduty customers tow more than 10,000 pounds. He also indicated that a large percentage of F-150 owners also tow in excess of 10,000 pounds.

So now that we recognize BEVs are not currently feasible for the over 150 million trucks towing over 10,000 pounds, it brings us to the realization that ICEs are going to be with us far into the future. That should be a problem easily handled. We know a lot about these engines so there should not be any problem other than in the normal course of development. Sounds right, doesn’t it?

Fuel use is going to be a major determining factor related to diesel engine oil choice. Commercial diesel fuel will still be available for the foreseeable future, so there will definitively be a need for API CK-4 and whatever follows. Don’t throw away your current oil!

However, there are fuels beginning to appear on the market that are believed to be more environmentally benign. These include bio- diesel and blends containing plant-based components. There are processes that convert them into a form of more diesel-like molecules. My concern is based on when the use of these components were first proposed for use as fuel. 

At an ASTM meeting 15 years ago, some data were presented showing the effects of various levels of biodiesel in Caterpillar 1N single-cylinder engine tests. As I recall, at 10% biodiesel in the fuel blend there was no major problem. However, when the biodiesel level was raised to 20%, unacceptable deposits were created in the test. I am too far removed from current additive technology to determine what changes were made in order to deal with the issue. The question for me is, what would 100% biodiesel require in the way of additive technology to be successful and viable?

My guess is that oxidation resistance will need to be improved, since biodiesel has some different chemical species that may not be as stable as petroleum products. In addition, detergents and dispersants will need to be rebalanced. I also suspect that somewhat different anti-wear chemistry will be needed. I believe that lower-viscosity base oils will be needed to satisfy finished oil viscosity grades—not a major change, but it will require reformulations. I do wonder if this oil will be suitable for CK-4 service. The oil industry, and particularly major fleet customers, want one oil for all their engine service needs. Stay tuned, as I think this may be the one to go first.

That’s the easy one. There is also a lot of discussion about gaseous fuels. Natural gas is not particularly unusual as a fuel to power engines; however, the engines are usually large stationary ones. Back in my old Pennzoil days, we recommended a straight grade SAE 30 Pennzoil motor oil for use in automobiles and light trucks that had been modified to burn natural gas. The recommendation was very successful, even though the market size was quite small.

Industrial natural gas-fueled engines were a bit trickier. Many of these engines were used at remote sites such as offshore platforms. Many operators used Pennzoil’s heavy-duty engine oil because there were mixed engines, and the operators wanted to minimize inventories. However, there were some engines that required a specialized oil with lower sulfated ash and lowered zinc levels. Even more specialized were EMD (Electro-Motive Division) engine oils that could not tolerate engine oils with zinc in them. These engines were two-cycle and had silver alloy wrist pin bearings. Zinc reacted with the silver and caused premature bearing failures.

Natural gas engine oils specifically designed for larger engines have some additive components that are formulated into the oil. Because these engines run hotter than liquid-fueled engines, more antioxidants are required. Additional corrosion inhibitors are required due to the fact that natural gas usually carries some pretty significant levels of water. Dispersants are also included to minimize deposit formation. If zinc levels are reduced, additional anti-wear agents will be required.

Another gaseous fuel you may have heard about is hydrogen. In theory, hydrogen is a pretty good fuel. The exhaust gas contains only water vapor, which is ideal from an emissions point of view. The problem is that hydrogen causes embattlement of many metals and would require a major redesign of engine parts. There is always a “however,” and in the case of hydrogen, it can be used in fuel cells for an electric power plant. That work is underway at several vehicle designers and holds great promise. No engine lubricants are required.

So here’s the bottom line: BEVs are coming and will probably own the market over the next 30-40 years. As vehicle weight and loads go up, BEVs become less practical and ICEs continues to rule. For the ICE vehicles and stationary applications, fuel choice will dictate the engine oil type and characteristics. All of this is subject to technical breakthroughs, but have no fear: ICEs will still have a place in our world.  

Steve Swedberg is an industry consultant with over 40 years experience in lubricants, most notably with Pennzoil and Chevron Oronite. He is a longtime member of the American Chemical Society, ASTM International and SAE International, where he was chairman of Technical Committee 1 on automotive engine oils. He can be reached at