Engine Lubricants formulations and Future Trends and Challenges

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Challenges and opportunities for lubricants industry. Global Concerns leading to Global Regulations.
The automotive and heavy duty diesel industries are going through a period of rapid change. The lubricant industry is changing accordingly.

Key Trends and Challenges in Lubricant Formulations are these main factors:
• Emission regulations
• Extended ODI (Oil Drain Intervals)
• Fuel Economy
• Alternative Fuels


Emission regulations and emission control strategies
Approaches vary with OEMs, but involve some combination:
• Exhaust Gas Recirculation (EGR) – without or with external cooling
• Diesel Particulate Filter (DPF)
• Selective Catalyst Reduction (SCR)
• Caterpillar use proprietary ACERT TM system












Different approaches lead to specific lubricants needs. Nevertheless certain trends are common to most diesel powered engines.
• Engine lubricants
• Higher soot loading in the oil due to EGR
• Restrictions on SAPS (Sulphated Ash, Phosphorus and Sulphur) to protect after-treatment devices

Soot from Cooled EGR engines is unresponsive to conventional dispersants… step-out technologies required.


Restricted SAPS Environment and Sources of SAPS
• Sulphated Ash – Metal detergents, ZDDP antiwear additives
• Phosphorus – ZDDP antiwear additives
• Sulphur – ZDDP, certain metal detergents, additive diluents, basestock


Phosphorus – The industry is fully cognizant of the impact of “P” loading on catalyst efficiency in gasoline powered vehicles
• Long term trend is to reduced ZDDP in the oil
• Extent of reduction will be determined by engine durability
• Significant reductions beyond current levels will require development of new phos-free anti-wear technologies

Sulphur – With “S” largely eliminated from diesel fuel in developed markets, and the widespread use of Group II and III basestocks, focus on sulphur content is now on the additive systems.


Role of Metal Detergents in SAPS Constrained Environment.
Metal detergents are metallic salts of organic materialssuch as sulphonate, phenate and salicylate
• Some also contain metallic carbonate core to impart basicity oracid neutralization capability to the oil
• Common metals are calcium and magnesium
Detergents play an important role in providing essential piston cleanliness and acid neutralization capability
Correct choice can also play a role in reducing ash and sulphur. Specially tailored salicylates for crankcase lubricants can offer significant advantages, especially in extended drain and SAPS constrained applications.


The Struggle to Reduce Ash : Calcium versus Magnesium
• Existing magnesium detergents can play an important role in reducing ash content in the oil
• However, large step-change reductions in ash from thecurrent levels will require development of non-metallic detergent and TBN systems


Extended Drain intervals:
Extended drain oils have broad appeal to the lubricant industry
• Optimum use of natural resources
• Cost of ownership - reduced downtime for fleet operators, reduced cost of disposal
• Marketing feature for OEMs

Drain intervals are in part constrained by: Emission control systems – soot loading in EGR engines, DPF and Concerns about engine durability.


Key enablers
• High quality basestocks – Group III, conventional as well as very high VI Group III’s
(example, from GTL – Gas to Liquid)
• Advanced additive technologies such as salicylate detergents,enhanced low S/P anti-wear and new antioxidant technologies
• Interestingly, viscosity modifiers also play key role – a fact generally not well understood in the industry

 

Role of Viscosity Modifiers
• Basic rule of lubrication: If the engine starts, oil must pump
• Not just when the oil is fresh, but all through its life in the engine
• Oils formulated with certain viscosity modifiers can experience serious loss of pumpability at low temperatures due to ageing in the engine
• For such oils, extending the time between oil changes can dramatically increase the risk of lubrication failure
• Careful selection of VM is critically important in extended drain applications

 
Fuel Economy
Fuel efficiency has been an important consideration for the vehicle manufactures for quite some time
Escalating fuel costs in recent times have further raised the profile of FE in the automotive as well as the heavy duty diesel engine industry. Large share of the Fuel economy -FE gains will accrue from innovations in hardware designs. However, lubricants can also play an important role in minimizing energy losses in the engine and, indeed the entire drive train. Tough GHG regulations are coming into effect in all major markets.


Typical energy distribution in a vehicle

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Fuel Economy Triangle

  • Boundary Friction – Friction modifiers
  • Rheological Losses – Lubricant viscosity
  • In-Service Retention – Volatility and durable friction modifiers


Real FE gains in engine lubricants will involve all three corners of the triangle!


Low Viscosity Lubricants
Low viscosity lubricants are becoming an increasingly important element in the race for higher FE.
For gasoline engines, SAE 0W-20 are not far away. Most of Japan cars manufactures, OEM's already aproved SAE 0W-20 oils.
For Heavy Duty - HD diesel engines, SAE 5W-30 and 5W-40 synthetic oils are starting to gain market.
Further reductions in viscosity will need careful attention both from engine designers and oil formulators!
HTHS viscosity is widely seen as the most critical lubricant property for fuel economy.
Lower HTHS -> Higher FE

Lubricants have to deliver FE-fuel economy performance, throughout their life in the engine, not just when they are fresh.
• Durable friction modifiers
• Antiwear system
• Low volatility
• Antioxidants
• Dispersants – particularly for soot induced viscosity control in
• HD diesel engine oils
Group III basestocks will play a major role in FE retention due to their low volatility superior antioxidant response high viscosity index.


Alternate Fuels

Use of biomass derived fuels to extend conventional fuels is gaining momentum
• Renewable energy source
• Security of energy supply
• Often price supported through government incentives

Gasoline – Use of ethanol is growing, particularly in NA
• 10% ethanol has been used as oxygenate in gasoline for longtime
• Recently E85 (85% ethanol) has been gathering momentum
• Some Brazil experience suggests that E85 will require oil formulators to address issues such as rust and emulsion

Diesel – Issues are much bigger here compared to gasoline because of the wide chemical and physical variety of alternatives being proposed.


Bio-Diesel
Derived from renewable resources, the use of FAME
(Fatty Acid Methyl Ester) in diesel engines has been spreading across the globe.
FAME is generally blended with petroleum diesel Designated “BX”, X = % of FAME in blend EG, B5 = 5% FAME, 95% petroleum based diesel. Positions of HD diesel engine OEMs vary widely B5 is generally accepted provided the FAME meets US or EU fuels specs. Some OEMs allow B20 and B30 for specific engines but may require additional monitoring. Use of B100 is rare but does exist – mainly in captive fleets.


What’s in a FAME?
FAME is manufactured from a variety of vegetable and animal sources
RME - Rapeseed methyl ester
SME - Soybean methyl ester
PME - Palm oil methyl ester etc...


The use of bio-diesel has a number of potential issues:
Diversity of sources - variable quality
Unsaturation in the backbone -oxidation
Presence of wax or wax-like structures - low temperature fluidity
Boiling range is typical higher than petroleum diesel accumulation of unburnt or partially burnt FAME in the oil


Effect on Lubricant Performance
Two oil quality levels, standard and top tier, were tested with varying levels of bio-diesel contamination for corrosion (Cummins HTCBT test), oxidation (GFC oxidation test), deposits (TEOST MHT-4 test), Low temperature fluidity.


Summary and Conclusions
As the needs and expectations of the engine OEMs and the lubrication industry are changing, lubes producers, blenders and the additive suppliers is rapidly adapting to the changes around it.
Evolutionary approaches will continue to play a role in lubricant formulations of the future.
However, real step-out changes in the additive technologies are taking place to address the longer.
term needs of the industry. Such changes will affect not just one or two classes of additives, they will affect almost every major type of additive component used in oil formulations.

These are challenging times for everyone in the value chain – OEMs, oil manufacturers, oil marketers and additive suppliers. Passion for innovation and perseverance will be key assets in this environment.

 

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