Are Low Viscosity Oils Harmful To My Engine?

Yes they are—zero-weight oils are becoming popular for fuel efficiency but often compromise on long-term engine protection. BestLine Racing Engine Oil Additives Can Help. Here's why:

1. Viscosity and Friction: Zero-weight oils (like 0W-20 or 0W-16) are thinner and flow more easily, especially in cold starts, reducing friction and improving fuel efficiency. Thinner oils create less resistance as they circulate, which in turn decreases the load on the engine and helps with fuel economy.

2. Lubrication and Protection: However, these oils may lack the "film strength" or thickness to maintain strong protective barriers, especially under high-load or high-temperature conditions. This can increase metal-on-metal contact between engine parts, potentially accelerating wear. Engine oils usually rely on a balance between viscosity and additive chemistry to maintain lubrication. With thinner oils, there’s inherently less "cushion" between moving parts, meaning less protection for critical components.

3. Additive Strain: Zero-weight oils need more advanced additives to compensate for their thinness, which can help but also lead to faster degradation of these additives under heavy-duty use, like towing or high-speed driving. This degradation reduces their effectiveness over time, further compromising engine protection.

For truckers or anyone running vehicles with high mileage or heavy loads, thicker oils (such as 5W-30 or 10W-40) or treatments that increase film strength can often offer better long-term engine health, even if they slightly impact fuel economy.

Several technical studies explore the trade-offs in using ultra-low viscosity or zero-weight engine oils, highlighting the tension between fuel efficiency gains and potential wear on engine components. For instance, recent SAE papers discuss how these thinner oils reduce friction losses and improve fuel economy by allowing for easier oil flow and less churning resistance within the engine. However, they also emphasize that ultra-low viscosity oils may compromise protective lubrication, particularly under high load or high-temperature conditions. This can lead to increased wear, especially on components like the valve-train in flat-tappet cam engines or other high-stress areas.

A 2023 SAE paper indicates that even with improved formulations, managing wear and oxidative stability remains a challenge with low-viscosity oils, as these properties can degrade with thinner lubricants more rapidly than with traditional oils. Another study from 2019 explains that results from standardized fuel economy tests may not consistently apply to all engines, meaning the wear and performance impact varies significantly across different engine designs and usage patterns.

For additional scientific insights, you may find papers like "Improving Fuel Economy without Compromising Wear" and "Engine Oil Fuel Economy: Benefits and Potential Debits of Low Viscosity Engine Oil" particularly informative, both of which examine advanced formulations aimed at balancing fuel economy and engine protection​