How do engine oils influence fuel economy?

Four main areas contribute to energy loss through engine friction:

Piston and Cylinder: The pistons and rings account for about half of the total engine friction. Energy loss occurs at the piston liner interface during the combustion cycle.

Valvetrain: The valvetrain friction can significantly contribute to overall engine friction, especially at low engine RPM, typically within the camshaft bearings and between the valve and lifter.

Oil Pump: During engine warm-up, energy loss often occurs due to the consumption of high-viscosity oils by the oil pump.

Crankshaft: Friction usually occurs in the main bearings and connecting rod bearings.

While lower-viscosity oils enhance fuel economy and reduce emissions, higher-viscosity oils generally provide better protection for the engine’s moving parts. Thus, the challenge lies in finding an engine oil that balances fuel economy and engine protection. The ideal oil should be viscous enough to separate critical engine parts yet thin enough to promote fuel-efficient engine operation. It is important to remember that sacrificing engine protection for reduced fuel consumption is not a worthy trade-off.

Switching to low-viscosity engine oils, like TRUCK-GUARD Elite lubricants, can minimise engine friction, allowing the oil to circulate more efficiently within the engine. This improved circulation enables the engine to operate more efficiently, resulting in lower fuel consumption while safeguarding the engine.

What cost benefits can we anticipate?

By transitioning from a standard 15W-40 to a modern, low-viscosity commercial lubricant like TRUCK-GUARD Elite 5W-30, fuel costs for a Heavy Goods Vehicle (HGV) can typically be reduced by 0.5% to 1.5%.

Newer API CK-4 and FA-4 oils are crafted for demanding conditions, lower viscosity, and fuel-efficient specifications. These high-temperature, high-shear (HTHS) oils flow between engine parts with less resistance, operating at high speeds and under elevated temperatures.

The latest lubricants offer further opportunities for fuel economy improvements. By upgrading to the more fuel-efficient FA-4 variant of the same grade, fleets could see additional fuel savings of between 0.4% and 0.7%. Therefore, a fleet upgrading from 15W-40 to a 5W/10W-30 FA-4 engine oil could experience fuel savings ranging from 0.9% to 2.2%.

However, while CK-4 oils are compatible with older vehicle models, FA-4 oils are not. FA-4 oils, with their lower viscosity HTHS, are designed specifically for vehicles manufactured from 2017 onwards when Original Equipment Manufacturers (OEMs) approved their use.

What are API CK-4 and API FA-4?

API CK-4 and FA-4 are categories of engine oils introduced in 2016 and established by the American Petroleum Institute (API). These categories are part of the API’s system for classifying diesel engine oils according to their performance characteristics.

API CK-4: API CK-4 oils are designed to provide improved high-temperature oxidation resistance, shear stability, and aeration control compared to previous categories. They are suitable for various engines, including older models. They can be used in various applications, including high-speed four-stroke diesel engines designed to meet 2017 model year on-highway and Tier 4 non-road exhaust emission standards. These oils are backwards compatible with most applications where older API “C” category oils were recommended.

API FA-4: API FA-4 oils share similar characteristics with CK-4 oils but are typically formulated at a lower viscosity grade. The goal of FA-4 oils is to provide further enhancements in fuel economy and reduce greenhouse gas emissions. However, these oils are not backwards compatible with as many engine models as CK-4 oils are. They are intended primarily for next-generation engines, specifically those typically manufactured from 2017 onwards, where high-temperature high-shear (HTHS) viscosity requirements are lower than in previous generations.

Following the vehicle manufacturer’s recommendations when choosing engine oil is crucial to ensure compatibility and optimal performance, and the significance of selecting the most efficient oil for your fleet cannot be overstated. Choosing one of our latest TRUCK-GUARD low-viscosity products can offer a significant economic advantage and cost-saving over a conventional lubricant.

Where to go next?

Find out more information about TRUCK-GUARD ELITE LS-FE 5W-30, our premier FA-4 accredited product, or our range of CK-4 accredited products. Alternatively, contact us today to discuss your lubricant requirements for your commercial fleet.