ALS Tribology eSource
March 2011

Lowering Viscosity CJ-4 Specification OilsSepia Truck
by David Doyle, CLS, OMA I & II
Vice President & Operations Manager

Trends toward lower viscosity CJ-4 oils will coincide with new 2014 federal fuel efficiency standards for over-the-road heavy duty diesel engines. OEMs are looking at lower viscosity CJ-4 oils as one of many ways to improve fuel economy in order meet the 2014 fuel efficiency requirements. There is currently a selection of SAE 10W30 engine oils that meet the CJ-4 requirement, with SAE 5W30 formulation now showing up on the market.

Lower viscosity HD diesel engine oils will be required to meet API/OEM approval so that engine manufacturers will know the fuel economy oils are still going to protect engines and not cause warranty claims to occur.  OEMs are very conscientious not to lose durability when moving to lower viscosity fluids, which will require oil formulations to meet the API performance requirements for engine protection and lubricant life. OEMs who do not manufacture engines for over-the-road applications (such as construction) may not see the need or desire to use a lower viscosity HD oil. Formulation changes to meet CJ-4 requirements for a lower viscosity oil can include friction modifiers or synthetic blends in order to maintain needed lubricity characteristics.  

The upcoming fuel requirements for diesel engines in 2014 are tied to longer range requirements for fuel economy by the National Highway Traffic Safety Administration (NHTSA) and emission controls by the Environmental Protection Agency (EPA). The table shown below is from a regulatory announcement from EPA and NHTSA for a proposed program for continued reduction in greenhouse gas emissions and improved fuel efficiency of medium and heavy duty diesel engines:

“The standards would phase in to the 2017 levels shown in Table 1. These proposed standards would achieve from seven to 20 percent reduction in emissions and fuel consumption from affected tractors over the 2010 baselines.”

Table 1: Proposed MY 2017 Combination Tractor Standards

 

EPA Emissions Standards
(g CO2/ton-mile)

NHTSA Fuel Consumption Standards (gal/1,000 ton-mile)

 

Low Roof

Mid Roof

High Roof

Low Roof

Mid Roof

High Roof

Day Cab Class 7

103

103

116

10.1

10.1

11.4

Day Cab Class 8

78

78

86

7.7

7.7

8.5

Sleeper Cab Class 8

64

69

71

6.3

6.8

7.0

Oil analysis will continue to provide critical information as we move toward changes in engine designs to meet regulatory requirements.  Maintaining the proper lower viscosity range for these new formulation diesel engine oils while in service will be necessary for ensuring fuel economy benefits. Monitoring the condition of the lubricant while in service will aid in determining when to change out the oil and optimize drain intervals

Return Home