Ultra-Thin Oils

With the fast approaching launch of the new ILSAC GF-6 standard for vehicle motor oils, more information is slowly becoming available as to what blenders and vehicle owners can expect from the new specification. What is coming into focus is that new engine technologies and more stringent emissions standards joined with new mileage goals for vehicles are going to make these new GF-6 oils work harder than ever before.

These oils will be a lot thinner and more robust than what people have been used to, with approvals for an ultra-thin viscosity grade, 0W-16/SAE 16 being given the go-ahead under the ILSAC GF-6 moniker.

What is driving this? The need to meet new United States federal guidelines for improved fuel efficiency and emissions.

“The main driving force is certainly fuel economy,” says Kristin Kowolik, consumer product specialist and member of the Chevron Lubricants Product Life Cycle Management Team. “The current CAFE (Corporate Average Fuel Economy) standard for average required fuel economy is 34.9 mpg. In 2016, this requirement will go up to 37.8 mpg.”

By 2025, all vehicles and light-duty trucks sold in the United States will have to post 54.5 mpg of fuel efficiency, a near doubling of today’s approved mileage standard. They will also have to produce significantly lower emissions as well.

To meet those standards, car makers are pushing engine designs to improve fuel efficiency and to reduce emissions, says Oliver Kuhn, who works in research and development with the German-based oil blender Liqui Moly. And the way to do that is to have engines that can operate using thin motor oils.

“Thin oil shows less inner friction and thereby reduces the overall friction in the engine,” Kuhn continues. “Thin oil is one tool in the car manufacturers’ toolbox to reduce the ecological footprint of combustion engines.”

“It is Honda who is driving this program and is the main driver for this new GF-6 [thin] oil,” says André Bolduc, product manager, lubricants and car care with Auto-Camping Ltd. “Fuel economy and direct injection engines with turbochargers are pushing this. These engines have smaller displacements. In Europe, you have 1.8 litre engines in E-Class Mercedes. That is a pretty small engine, one that we once saw in the old Rabbit which was a much smaller car that today’s [Volkswagen] Golf. But you now have these small displacement engines in mid-sized vehicles. These are very high-tech engines that work much more powerfully than before.”

This is placing unique challenges on oil blenders as these new thin ILSAC GF-6 motor oils have to meet stringent specifications. Ian Hutchison, brand manager, Castrol Automotive with Wakefield Canada, says these will include: increased fuel economy throughout the oil change interval; enhanced oil robustness; protection against low-speed pre-ignition; improved wear protection for ‘idle stop’ engines; and reduced aeration over the entire oil change interval.

But some engine makers are pushing engine designs that can operate on oils that are going to be even thinner than the 0W-20/SAE 20 motor oils that are going to be coming out under the ILSAC GF-6 specifications. Honda is developing and will soon roll out engines that operate on oils that will have a 0W-16 viscosity grade approved by the SAE.

“SAE 0W-16 oils represent the new, lowest SAE oil viscosity classification defined by this technical organization,” says Scott Lindholm, Pennzoil global product applications specialist. “SAE 0W-16 oils are ‘thinner’ at high temperatures than other oils, SAE 0W-20, 5W-20, 5W-30, etc., in order to reduce losses from pumping thick oils in an engine to improve fuel economy. SAE 0W-16 oil development is just one of the many engineering efforts to help automakers achieve the 54.5 miles per gallon target established for 2025. Of course, the challenge is to provide very thin oils that also provide wear protection.”

No two ways about it, it is going to be a difficult balancing act.

“Basically, there are two ways to reduce the motor oil’s viscosity,” says Liqui Moly’s Kuhn. “First, we can use thinner base oils — but then the motor oil suffers from higher evaporation losses. Second, we can use less viscosity improvers on the additive side. Already, today’s thinner oils like 0W-20 contain significantly less viscosity improvers compared to let’s say a 10W-40 oil. The true challenge for SAE 16 oil is the lubrication. A basic lubrication is ensured by the base oil. But the thinner the base oil, the less effective is this ‘natural’ lubrication and the more important is the lubricating performance of the additive packages. This is where lots of the research resources are invested right now, in developing next generation additives with improved lubrication properties.”

Wakefield’s Hutchison says there will have to be a balance between how thin the oil can become while still lubricating critical engine components. Not striking that balance means the engine will either not achieve the needed fuel economy or it will experience more wear and tear.

Hutchison explained this in greater detail in an email: “A lubricant must maintain a certain minimum sheared viscosity in order to provide adequate hydrodynamic lubricant and prevent friction between moving parts from causing wear. Of course, with today’s additive technology, friction modifiers, ZDDPs, and shear stable polymers [it] allows us to reach lower SAE viscosity grades than ever before. The new SAE 16 grade that is being introduced with GF-6 for fuel economy benefits is a prime example. In order to ensure that wear protection is not compromised by fuel efficiency improvements, the SAE J300 spec for this new SAE 16 viscosity grade must have a minimum High Temp/High Shear viscosity.”

One of the issues that will surround this new ultra-thin SAE 0W-16 oil is that it is not designed to be backwards compatible, meaning that is should not and cannot be used in today’s GF-5 engines, says Robert Skaggs, vice-president, sales and marketing, Blue Water Group, the distributor of Mobil Lubricants. “This new J300 initiative is meant to address the high temperature grade range (i.e. SAE 20, 30, 40, etc.) of multi-grade oils with no change being effected on the low temperature grade range (SAE 0W, 5W, 10W, etc.). The primary aspect is to directly affect the ‘flow characteristics’ of the high temperature range – thinner = greater flow characteristics = less friction/drag in the engine = better fuel economy. Yes, the kinematic viscosity will be much better as well – 6.1 mm2/s minimum to <8.2 mm2/s maximum, at 100 degrees C.

“The minimum high temperature high-shear rate viscosity is 2.3 mPa•sec at 150 C. (As a reference, the kinematic viscosity of 0W20 via J300 will be revised as an SAE 20 oil’s kinematic viscosity, which currently is measured at 100°C (212°F) and was 5.6 cSt to less than 9.3 cSt. Under the new J300, the minimum kinematic viscosity will be increased to 6.9 cSt to bring the range of SAE 20 in line with that of the higher-viscosity grades). Viscosity modifiers (and to a lesser degree friction modifiers) will play a major role, additive wise, in gaining the benefits required.

“For the layman, the message is increased fuel economy with superior ‘stay in grade’ capability. The 0W16 will differentiate itself from today’s oils by using a proprietary additive package designed specifically for this grade to enable it to maintain both fuel economy gains with the ability to stay in grade during drain intervals as set out by the OEM.”

What technicians need to know is that because these oils are not backwards compatible, they can only be used with vehicle engines that are specifically rated and designed to use them, says Thom Smith, vice-president, branded lubricant technology with Ashland Inc. “You just can’t take your car that is doing a 05W-30 motor oil and think you will get better fuel economy by pouring in a 0W-16 motor oil. You will risk doing some serious damage to the engine if that engine has not been designed to use that specific grade of oil.

“As we go to the smaller displacement engine with turbochargers, they will be running hotter and there will be greater stress put on the oil, so we expect we will need higher levels of antioxidants, more thermal stable detergents and more dispersants to keep the engines clean.”

Because of the risk of accidentally pouring an SAE 0W-16 oil into a vehicle not rated for it, there are already moves to develop a clear identification between SAE 0W-16 oils and the other oils to come out under the GF-6 specification. One suggestion is to identify SAE 0W-16 oils with a GF-6B specification.

“The SAE 0W-16 grade will clearly be identified with the new viscosity grade clearly shown on the label of the engine oil as all viscosity grades are now,” says Pennzoil’s Lindholm. “There is consideration being given by API to the use of a unique symbol to aid in the identification of low viscosity oils which may be suitable for use only in engines designed for these low viscosity products.”

“There are discussions among industry leaders of having a unique ILSAC starburst symbol for the new viscosity grades but nothing has been decided or finalized yet,” adds Chevron’s Kowolik. “ILSAC GF-6 will be split into two categories. ILSAC GF-6 A will include all current viscosity grades and will be backwards compatible. ILSAC GF-6 B will include the new lower viscosity grades, will not be backwards compatible and will be OEM dependent. The introduction of GF-6 and these new viscosity grades will certainly introduce some confusion not only for consumers but also for marketer, distributors and quick-lube facilities. Educating the public will be crucial.

“Viscosity grades usually go up and down in multiples of 5 (for example SAE 0W-20 and SAE 0W-30). While trying to come up with a new viscosity grade designation, industry leaders wanted to avoid confusion and decided not to introduce SAE 15 oils. 15W-40 is one of the most popular viscosity grades in the heavy duty market and consumers could have mistakenly put heavy duty oil into a passenger car. SAE 16 category was adopted instead to ensure that there was no misalignment between the oil and the correct application.”

“At the moment, it is not clear how API will handle this issue,” adds Liqui Moly’s Kuhn. “But, of course, clear labeling is crucial in order not to confuse consumers as well as professionals. GF-6 will be compatible to GF-5, whereas GF-6B with SAE 16 will be a class of its own. The letter ‘B’ means a huge difference.”

“GF-6B will be completely unrelated to GF-5 and will be even lower viscosity leading to a unique formulating approach where the base oil selection, the balance of additive, and the viscosity modifier will all be critical aspects,” says Antonio Ramos, marketing manager with Automobile Solutions Americas Inc., distributor of the Veedol line of lubricants. “The proposed GF-6B oils would provide the same performance as GF-6A, but with the aim of lower HTHS to deliver potential fuel economy benefits. This offers the possibility of potential GF-6B oils operating at viscosity ranges of less than 0W-20 once these new viscosity grades are defined and accepted by SAE.”