Oxidation Stability in PC-11 Oils: A Critical Factor in Oil Performance and Engine Life

by on June 21, 2016 3 Comments

RustyEngine_Blog_061516In our last PC-11 related blog, we outlined the three key traits to look for in the new engine oil categories coming out of the PC-11 initiative, API CK-4 and FA-4. Now, let’s zero in on one of those traits, which is getting a lot of attention these days: oxidation stability.

In general, an engine oil has two main functions: 1) to protect the engine, and 2) to protect itself from breaking down. High levels of oxidation drive a higher propensity for oil to break down, thicken in viscosity, form deposits and even cause corrosion of certain engine parts, which could lead to premature engine failure.


Extending Oil Drain Through Better Oxidation

In fact, oxidation is the primary reason oil has to be changed as often as it does today. Modern engines do not produce as much soot or sulfuric acids as they did 15 years ago, meaning oils are less likely to degrade due to soot accumulation or total base number (TBN) depletion. The greater risk for breakdown today is prolonged high temperature exposure causing higher oxidation. The new API CK-4 and FA-4 oils are required to improve in oxidation control over previous categories.

The new Volvo T-13 test focuses exclusively on oxidation control in the new API categories. It measures oxidation levels and viscosity change in oils exposed to temperatures up to 130o centigrade over 360 hours, pushing the oil to the very limits of what is practical. In reality, an oil is not likely to experience that level of heat, though it may for short bursts of time. Additives are required to balance the effects of oxidation and reduce the risk of breakdown. You can compare oil breakdown to food spoilage, which also is caused by oxidation and additives are used to mitigate the process.


A Change for the Better

What we are seeing is that the new oils are definitely more robust in high-temperature operation compared to today’s products. With a much lower propensity to break down, engine manufacturers may well be compelled to extend their drain interval recommendations for API CK-4 and FA-4 oils.

These benefits are relevant to both on- and off-highway applications, perhaps even more so for off-highway, where equipment often operates at higher temperatures under severe duty conditions. In either case, the combination of longer drain intervals and lower risk of engine failure should help drive lower operating costs and a greater return on investment in equipment – the bottom-line reasons for choosing any motor oil.

With Delo products, our goal is to achieve “flatline” performance in various tests, meaning that the viscosity of a used oil that has had prolonged high-temperature exposure is not much different from that of a fresh oil. For more information, please visit: www.PC-11Explained.com.


NOTE: This is the second part of a 4-part series focusing on the key traits to look for in CK-4 and FA-4 oils.



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About the Author ()

Shawn’s career spans nearly 20 years focused exclusively on research and engineering dealing with heavy-duty engine lubricants, fuels, and materials. Before joining Chevron in 2013, he spent 12 years leading global fluids and materials engineering activities for Cummins. He also spent five years conducting lubricant, fuel, and emission research for the Department of Energy’s National Renewable Energy Laboratory in Golden, CO. At Chevron, he is a Senior Staff Engineer primarily responsible for product formulation of the Delo Brand of Heavy Duty Engine Oils. He is currently the lead formulator responsible for development of Chevron’s PC-11 product line upgrade. Whitacre is the new chairman of the ASTM Heavy-Duty Engine Oil Classification Panel, which is tasked with the final development of the Proposed Category 11 (PC-11) requirements that take effect in late 2016.

Comments (3)

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  1. Dan Holdmeyer says:

    The new HDMO API CK-4 is not only important to on-highway but also beneficial for the hot, hard working, off-highway engines.

  2. jmbaxt@aol.com' John Baxter says:

    This is a very interesting piece. The fact that even if a fleet must use CK-4 rather than being able to capitalize on the lower HT/HS viscosity of FA-4, they can benefit from an improvement in oxidation stability is pretty exciting!

  3. stephentweneboah@gmail.com' Stephen Tweneboah says:

    What you have written is very good. I will use them to explain to my receipients. Thank you so much.


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