“Most people associate higher viscosity with better engine protection, but that sentiment is breaking down, because it isn’t true.”
Oil Company Engineer
In a truck’s engine, mechanical losses from pumping and friction consume approximately 16% of the total energy input of the vehicle. Lower viscosity oils—oils with less internal resistance to flow—will reduce these engine mechanical losses, thereby reducing fuel use.
Since 2003 fleets have been ramping up their investment in lower-viscosity lubricants. Yet while 40% of the largest, most efficiency-conscious fleets have adopted these engine oils, the adoption rates for the industry as a whole remain at only about 20%. However, new emissions regulations and the advent of new oil categories may increase the adoption rate.
- 0.5% – 1.5% when switching from 15W-40 to 5W/10W-30
- 0.4% – -0.7% when switching to FA-4 oils, available after December 2016 from CJ-4/CK-4 5/10W-30 oils
- Ability to extend oil drain varies, but one fleet expects to extended its drain interval by 20,000 miles
- Increased costs for fleets using non-synthetic 15W-40 oils because most 15W-40 oils are mineral based and most low-viscosity oils are synthetic or synthetic blend
- 30% to 40% cost increase when switching from a mineral-based to a synthetic-based oil
Case Study: National Truckload Carrier
The national carrier had been using a 15W-40 mineral-based oil. An oil supplier approached the carrier to test 10W-30 engine oil. The fleet agreed to the test to improve cold-weather starting and fuel efficiency.
Case Study: Carrier with Dedicated Operations
The national truckload carrier had considered switching to a 10W-30 oil. The fleet manager consulted with the engine supplier about available options.
The study team developed three tools to help fleets make decisions about low-viscosity engine oil.