Engine and drivetrain

TLT Sounding Board July 2022

 



Executive Summary
Efforts to improve fuel economy are an important piece of broader sustainability and efficiency goals in the automotive industry. While engine oils have already been developed with lower viscosities to meet the needs of more efficient engines, many readers think manufacturers will continue to develop even lower viscosity grades. Other readers believe that the industry has approached optimization in this area and will focus resources on other areas such as electric vehicles instead. The majority of readers agree that regardless of how the viscosity grades change in the next decade, the development of new additives will increase, as will innovation in terms of new engine designs.
 
Q. Over the next five to 10 years, how far will we see the drive to increased fuel economy move us to lower viscosity grade engine oils?

Sharp increase.

In fact, I expect viscosities to drop even further, right down to water-based lubricants.

I work directly with many manufacturers, and all of them are saying they will definitely be moving to lower viscosity grades in the future.

It will accelerate to 0W-16 and 0W-8 or lower.

With so much move toward electrification, it could be that less attention will go toward lowering viscosity any further than it has in the last few years.

We will go to 0W-4.

Trying to “extend” the useful life of gasoline engines will be seen as a lost endeavor if governments keep pushing for an all-electric design model, either by subsidies to corporations or rebate programs for drivers. I believe the shift will be more toward electric vehicles until such time as governments realize that consumers aren’t willing (or able) to wait for charging to take place during the day—at which point a push toward a “refillable” vehicle design is embraced, i.e., hydrogen. Clean hydrogen (via fuel cell) is perhaps the only practical solution for passenger vehicles, with an internal combustion hydrogen engine as an interim solution, requiring the use of engines oils.

Partial way.

It’s difficult to say, but thinner oils will be needed as new engines are designed for further improved efficiency. The ongoing shift for electrified drivetrains will particularly drive the shift for thinner e-type transmission oils.

Do you think we will see new and lower SAE viscosity grades (below 0W-8)?
Yes 48%
No 52%
Based on an informal poll sent to 15,000 TLT readers.

Oil viscosity will be reduced a bit as we are close to its optimal value. New oil additives developments will increase the fuel of the internal combustion engine (ICE) economy. It will provide an additional competitive advantage with electric vehicles.

0W-8 should be common in new vehicles in five to 10 years.

My limited knowledge on this particular topic says to me, “How low can it go?” I understand it’s already down to SAE 8. I tend to think there will be more push to eliminate internal combustion altogether than what is gained in lowering engine oil viscosity lower than 8. That’s not to say, however, that there will never be grades lower than SAE 8.

Do you think we will see engine oil viscosities defined differently from the current SAE method?
Yes 45%
No 55%
Based on an informal poll sent to 15,000 TLT readers.

It will happen slowly but it will happen—although, in my opinion, engine oils for passenger vehicles are already at the point of being at the minimum required and useful viscosity.

This may be more than 10 years out. We may see engines, especially on the diesel side, lubricated with the fuel rather than a separate engine oil.

0W-8. That’s probably low enough to take us to the end of large scale production of the ICE.

Lower viscosity grades, higher viscosity index and lower high-temperature high-shear viscosity at approximately 80 C (HTHS80).

I do not think we will be able to go much lower than 0W-8 without increasing volatility and/or wear for standard-fueled ICE engines, especially during the time frame given. Green biofuels (including hydrogen) for ICE and hybrid ICE engines are a whole new ballgame as far as oil requirements.

In my opinion, unless all engines changed to alternate fuels or electric technology, there is not likely a move to lower viscosity grade oils, since, in all engines, most of the engine speed and torque is the same, and viscosity specified by the OEM is to be maintained. Otherwise, you can increase fuel economy while sacrificing the power produced by the engine and increased wear in the lube system components.

Do you think the drive to lower viscosity grades will necessitate the development and deployment of new additives?
Yes 88%
No 12%
Based on an informal poll sent to 15,000 TLT readers.

We are at the endpoint now. The ICE cannot be improved any further in my opinion. Also, the electric vehicle will not have such a sensitive viscosity requirement. The electric vehicle may be better served with naphthenic oils rather than paraffinic oils. And molybdenum disulfide dry lubricant may very well be the panacea lubricant for the electric vehicle.

Oil viscosity index is crucial when drivetrain elements are running. It is selected to directly impact operational conditions to set minimum power loss and optimum film thickness from occurring. Over the next decade, any vehicle may not require higher speed more than now. Thus, just oil mechanical and thermal properties can be improved to get higher performance with the same drivetrain to get minimum loss of fuel.

Do you think engine oils for passenger cars are already seeing the minimum required and useful viscosity?
Yes 51%
No 49%
Based on an informal poll sent to 15,000 TLT readers.

I don’t think we’ll go any lower than the current 0W-8.

There will be a (temporary) move until electric vehicles have replaced the ICE. I think the push will be greatly slowed down due to vast quantities of development funds being spent on non-ICE drivetrains. Emphasis on electric drive fluids (EDFs) will suck attention and monetary and human capital away. The possibility of technical breakthroughs on the EDF side might feed technology back to ICE lubrication, but no sense of odds here. We have anecdotal evidence that OEMs are losing the ability to make ICE-related improvements due to shifts in staffing and will get much worse in the next five to 10 years.

About 10%.

To access increased fuel economy benefits from lower viscosity, do you think we will have to see radical and specific co-development of new engine designs?
Yes 71%
No 29%
Based on an informal poll sent to 15,000 TLT readers.

The number of different engine technologies produced that utilize 0W-16 and lower viscosity grades will continue to increase. However, I am not sure that viscosity grades below 0W-8 will be required, as it becomes very difficult to provide adequate lubricity in an ICE with such low viscosity. It may be possible that a hybrid engine that runs only for very short periods of time and maintains a relatively low temperature would be able to run at viscosities lower than 0W-8, but this will likely not become commonplace.
 
Editor’s Note: Sounding Board is based on an informal poll of 15,000 TLT readers. Views expressed are those of the respondents and do not reflect the opinions of the Society of Tribologists and Lubrication Engineers. STLE does not vouch for the technical accuracy of opinions expressed in Sounding Board, nor does inclusion of a comment represent an endorsement of the technology by STLE.