Why reefer fleets should consider low-viscosity engine oils

On-highway diesel prices have caused significant pain for all types of fleets this year. In pursuit of protecting the bottom line, fleet managers should be looking at any and all ways to boost fuel economy and control costs. For those fleets operating refrigerated trailer units, the complexities can become more challenging. Managing logistics while keeping both the trucks and refrigerated units they haul operating at optimized efficiency isn’t easy. But success in today’s business climate demands it.

To that end, refrigerated fleets should consider one particular route toward greater operational efficiency and fuel economy gains that has largely gone unexplored: the use of low-viscosity engine oils, including those certified to the American Petroleum Institute (API) FA-4 performance category. Low-viscosity lubricant formulations create less resistance between moving parts in an engine, and therefore can help deliver significant fuel economy benefits over a vehicle’s lifetime.  

There have been hurdles to widespread adoption, but they can be cleared by fleets armed with the right information and the right partners. This article explore the benefits refrigerated fleets stand to gain through the application of low-viscosity formulations, and how to get there.

Robust protection any fleet can count on

It’s worth noting that approximately 81% of heavy-duty diesel engine oils sold in North America—across all fleet types—are API CK-4 15W-40. No other available grade, including 10W-30 and 5W-30, breaks the 10% threshold.

Why? Part of the reason may be that conventional wisdom in the trucking industry holds that higher-viscosity lubricants provide better protection than thinner lubricants. But this mindset is outdated. Modern low-viscosity lubricant formulations deliver the same protective benefits to heavy-duty engines as their less efficient, high-viscosity counterparts, and it’s required for API certification. All lubricants meeting the API CK-4 and FA-4 performance categories must complete the same performance testing program in order to gain certification, no matter the viscosity grade.

The key difference between the categories is this: CK-4 defines conventional engine oil formulations that are backward compatible with older-model engines, while FA-4 was specifically developed to deliver enhanced fuel economy benefits in newer diesel engines. And while some North American truck original equipment manufacturers (OEMs) do not approve the use of FA-4 formulations in their vehicles (more on this later), consider that almost all of them factory fill new-model engines with CK-4 10W-30 grade engine oils.

Both API and OEMs are confident in the protection lower viscosities can provide for virtually all trucks on the road today. Fleet owners should share that confidence. Fleets that continue to fill their trucks with higher-viscosity grades are therefore missing out on some of the benefits lower-viscosity formulations can provide.

The issue of refrigeration OEM approvals

For refrigerated fleet operators, however, OEM approvals get trickier. This is because refrigerated unit manufacturers were not as involved with the API’s development of CK-4 and FA-4 as heavy-duty engine OEMs and have been recommending the standardized use of API CK-4 15W-40 lubricants for factory fill since the category’s inception. On the surface, this decision makes sense. Refrigerated units themselves do not stand to become more fuel efficient by using lower viscosities, making it reasonable to be apprehensive of a newer technology.

However, using CK-4 15W-40 limits the fleets options that can bring benefits to their overall operation. This is because most operators and service technicians prefer to use one type of oil throughout the entirety of the fleet. This, once again, is an understandable decision on the surface. Using one oil for both the refrigeration unit and the truck engine helps simplify maintenance procedures and prevents misapplication, functionally eliminating the possibility of a service technician filling an application with the wrong oil.

But this situation may prevent forward-thinking fleets from adopting lower-viscosity lubricants for use in their trucks, and therefore they may be leaving significant fuel efficiency benefits on the table. According to “Trucking Efficiency Confidence Report: Low-Viscosity Engine Lubricants,” a joint report from the North American Council for Freight Efficiency and Carbon War Room, the benefits of upgrading to low-viscosity formulations can be impactful. “Class 8 over-the-road fleets can realistically expect fuel savings in the range of 0.5%-1.5% by switching from 15W-40 to 5W/10W-30 engine oil,” the report says. FA-4 formulations can provide greater savings. “The savings from switching to the fuel-efficient FA-4 variant … can be expected to add a further 0.4%-0.7% of increased fuel efficiency.” Over time, these efficiency gains can accumulate into significant fuel savings, especially across larger fleets.

For these reasons, fleets operating large numbers of refrigerated units should consider whether the potential complexity of stocking two types of lubricants—lower viscosities for trucks, higher viscosities for refrigerated units—is worthwhile. It’s also worth remembering that FA-4 lubricants have been proven in the field in a wide variety of applications, including engines where these formulations have not been explicitly approved. Filling refrigerated units with FA-4 can allow fleets to simplify operations, helping protect critical assets while seizing the fuel economy benefits via enhanced truck performance.  

Advocating for lower viscosities

For the reasons examined here, refrigeration unit OEMs may recommend the use of FA-4 formulations in the near future. This would be beneficial for fleets that want to maintain simplified engine oil drain protocols while bolstering their bottom line with a solution that provides greater fuel efficiency at a time of skyrocketing fuel prices.

Interested in learning more about what low-viscosity engine oils can do in fleet operations? Start a conversation with an oil marketer and refrigerated unit OEM supplier. Additionally, it’s a good idea to reference a recently approved recommended practice from the Technology and Maintenance Council (TMC) that offers step-by-step assistance to selecting an ideal lubricant formulation.

In the face of today’s operational challenges, refrigerated fleets need every tool at their disposal to maintain efficiency and profitability. Low-viscosity lubricants can and should be a consideration in pursuit of those goals. 

Greg Matheson is a commercial lubricants product manager for The Lubrizol Corporation. Since joining Lubrizol in 2015, Greg has worked as an OEM account manager, managing Lubrizol’s business with the heavy-duty truck and engine builder OEMs in North America.  In his current role, Greg is responsible for a wide variety of API CK-4 and FA-4 additive products in North America and globally for Lubrizol.