Well, its that time of the year again, so before 2015 completely fades away I am going through readers notes, letters and comments to see what topics are of strongest interest to all of you. The list is as long as ever, and there are a number of good lessons to remind ourselves of, or to learn for the first time. Some of the comments are funny while others are very instructive, with even a gotcha or two.
In Aprils issue, I covered the move by Ryder Systems to use SAE 10W-30 engine oil for all their fleet of over 200,000 trucks, in place of the more commonly used SAE 15W-40. Scott Perry, Ryders vice president of supply management, told us that the change was for fuel economy purposes and the reduction in viscosity would result in fuel savings estimated at 1 to 1.5 percent.
However, I went off track a bit here and wrote that the high temperature, high shear rate viscosity limit for SAE 10W-30 was 2.9 centiPoise minimum. Thats correct – if youre dealing with gasoline-fueled engines. George Zhang of Valvoline and Shawn Whitacre from Chevron both corrected me, pointing out that heavy-duty diesel engine oils of this grade have a HTHS viscosity limit of 3.5 cP minimum. This is particularly relevant, Whitacre pointed out, given our upcoming transition to PC-11, which will place increased scrutiny on this parameter, and the potential confusion that could arise from the split category concept. At least its nice to know that people actually read the articles and keep me on track.
Junes column apparently struck a nerve. It dealt with the Law of Diminishing Returns as it applies to fuel economy mandates. My starting point was a U.S. Environmental Protection Agency graphic showing that as vehicle mileage continues to get better, the impact on fuel consumption becomes increasingly marginal.
The agencys graph showed that improving Corporate Average Fuel Economy from 10 mpg to 15 mpg resulted in a fuel savings of about 33 gallons per 1,000 miles of driving. Currently, we are moving from a mandated 27.5 miles per gallon to a CAFE requirement of 35.5 mpg. But at this level, the fuel savings is only about 6 gallons per 1,000 miles driven. This is called the MPG Illusion; that is, gallons consumed over a given distance is not the same as miles per gallon.
Reading this, Zephyr Moore wrote to press home the case for removing such frivolities as license-plate frames bearing the auto dealers name, since these weigh at least half a pound and all weight needs energy to push the vehicle forward. Zephyr didnt quantify the energy requirement to move such a small mass, and I confess I am a bit intimidated at the thought of calculating it (even if only an estimate) myself. Im a gamer, though, so I took a shot at it and came up with 20.4 joules to move that half-pound license plate holder at 30 mph. A 3,000-pound vehicle takes about 12298 joules to move at 30 mph. With my shaky analysis, I further surmise it might take about 0.15 percent additional energy to move the car with the license-plate holder. Maybe plastic would be a better choice.
Another reader, Tim Theriot from Chevron, had a good question regarding fuel economy benefits of engine oils. He wanted to know if the effect of fuel-saving engine oils is additive to changes in engine design, improved aerodynamics and other improvements when comparing the fuel economy performance of engine oils in Sequence VID engine tests. Will the results really be cumulative? he asked.Wouldnt the future, more fuel-efficient engines rely on lower viscosity oils to achieve the 2017 and 2025 CAFE requirements? Is this double-dipping?
That was a real tough one, and I had to struggle with an answer. My first shot discussed the changes rather than the direct question of whether the Sequence VID results actually added to the fuel economy performance or only supplemented them. To be honest, I dont know for sure what the answer is to that one. We all think in terms of additional performance, but engine test parameters only show how a particular oil formulation does when compared to a reference oil in one engine. The industry has agreed that those results are indicative of how the oil will do in other vehicles.
If you remember back to the beginning of our quest for fuel economy, the gold standard was originally a five-car test using actual vehicles run through specific duty cycles on a mileage accumulation dynamometer unit. The procedure was the same using a reference oil (an SAE 20W-30) versus the test oil. It was necessary to flush the engine between runs to make sure there was no so-called carryover effect. Of course there was some carryover, but the baseline was simply moved to account for it.
As you can imagine, running five full-sized cars on dynamometers was a very costly undertaking, so the oil and auto industries opted for a fired-engine test stand that would approximate the results from the five-car test. Thats how we got to where we are today. So the bottom line to Tims question is, I dont know if the fuel economy benefit is additive to the engineering changes or not.
In Engine Oil Life, Guaranteed in July, I wrote about proposed California legislation that would have required oil marketers to certify that their oils were suitable for use up to 10,000 miles. As most everyone recognizes, the oil industry is not the certifier of oil life. Drain intervals are the OEMs bailiwick, and their recommendations are based on specific vehicle engine designs coupled with driving cycles.
Theres no question that oil chemistry can help with product life. Such things as additive chemistry (deposit control, wear protection, oxidation resistance) can make a real difference. Hydrocracked base oils made a difference, too, thanks to their viscosity index, oxidative stability and lower volatility.
However, one reader, Wayne Owen, thought that I was missing the most obvious solution: synthetic engine oils. Wayne suggested that I was unaware of synthetics or had a prejudice against them, and pointed out that these have been in the marketplace for over 40 years.
For the record, I am well aware of synthetics and believe they have a definite place in the market. They can offer improved low- and high-temperature performance, as well as resistance to deposit formation and oxidation. My big reservation is an economic one, since synthetics are quite a bit more costly.
Oil consumption: A Problem No One Needs, came under the microscope in Octobers column. A number of auto manufacturers are being challenged in civil court about high oil consumption (requiring top-ups of as much as 1 quart per 500 miles). These were not older vehicles, but some new and pretty pricey models such as Audi, Mercedes and BMW, and popular cars from Subaru and Toyota.
That prodded Larry Solomon of Strategic Resources to drop me a note that is so telling I am going to quote a good deal of it here. First he noted that all his research, dating back to his days working for Valvoline, shows that eight out of 10 vehicle maintainers do not check or add oil between changes. So the oil industry knows that oil consumption would be less of a problem if vehicle maintainers would check their oil regularly.
When you and I were very young (circa 1950s), Larry added, my dad would pull in to get gasoline. The attendant would put gas in the car, lift up the hood and check all fluids. I worked at a gas station when in high school and we did that for customers. Now, it is rare that anyone lifts up their hood to replenish lost fluids.
Then there are the exchanges I had with Jim Newcombe, John Fischer, Mike McMillan and others, about the addition of new low-viscosity engine oil subcategories. In hot pursuit of fuel economy, the industry has decided to split the coming ILSAC GF-6 light-duty and PC-11 heavy-duty engine oil upgrades. These will be marketed respectively as GF-6A and 6B, and API CK-4 and FA-4, and consumers will have their work cut out to keep them straight.
Jim summed it up well by saying that it feels like the industry has lost its mind and forgotten its responsibility to clearly communicate with the ignorant consumer. Now retired, Jim was the longtime voice of Paramins and then Infineums annual Trends presentation. He has a long history as one of the leaders of the oil industrys efforts to develop meaningful standards to assist consumers in selecting the best oils for their vehicles.
In the perennial discussion about engine oil viscosity, Tina Dasbach from the Institute of Materials asked me what improvement in fuel economy we can expect from SAE XW-16 oils versus other grades such as SAE 0W-30. I responded with the comparative fuel economy targets for the next engine oil upgrade (ILSAC GF-6B), based on the anticipated Sequence VIE test limits.
However, Tina was thinking more about how much fuel economy benefit would be gained by comparing the limits of two grades. In my April column, I had noted that for GF-5 oils, the sum of fuel economy improvements over the span of the oils life must be at least 1.9 percent with SAE XW-30, but SAE XW-20 oils are required to show a minimum 2.5 percent improvement. So a vehicle manufacturer can capture 30 percent more fuel economy from the lighter weight oil. While that is correct when comparing Corporate Average Fuel Economy for different grades, it does not reflect the level of fuel savings in a vehicle.
The subject of viscosity leads directly to the topic of volatility. Of course, volatility relates to oil consumption, so were coming full circle. Central Petroleums Blaine Ballentine wrote to ask about volatility as it relates to viscosity. As viscosity goes up, volatility goes down, because both are related to the boiling range of the oil. You can vary the volatility of a viscosity cut by making the boiling range narrower (lower volatility) or wider (higher volatility). The impact of this choice is cost. Synthetics can make a difference here, since they tend to be lower in volatility for a given viscosity.
Once again, readers have delighted me with the fact that you read this column and ask very astute questions. Heres to 2016. May it be a great year for each of you, and keep reading LubesnGreases!
Industry consultant Steve Swedberg has over 40 years experience in lubricants, most notably with Pennzoil and Chevron Oronite. He is a longtime member of the American Chemical Society and SAE International, where he was chairman of Technical Committee 1 on automotive engine oils. He can be reached at steveswedberg@cox.net.
Please, No Lifting
Back in March, a reader Ill call Darren contacted me about including a copy of my February column, Volatility, Front and Center, on a website he was developing to help sales people understand our business better. Naturally I was flattered, but unfortunately for Darren, copying any LubesnGreases article, even with attribution, violates international copyright law. Thats because everything you read in LubesnGreases is provided for our own subscribers, not others.
Our editors clarified that Darren could describe a columns main point, paraphrase or even cite brief quotes from it (with attribution); he was also welcome to link to our digital edition so his website viewers could read the entire piece at its source. But reprinting a whole column or article is a no-no. So a word to the wise: Even though my prose is deathless, you cant copy it or put it on the internet without obtaining prior permission from LubesnGreases.
– Steve Swedberg