Overcoming Oxidation in Next Generation Engines - Whitepaper

Regulations driving improved fuel economy and reduced emissions have driven engine hardware changes, which have led to diesel engines running hotter. With higher operating temperatures comes additional challenges, including oxidation. Oxidation is a leading contributor to oil degradation and is accelerated at higher temperatures. It can lead to deposit build-up, increased viscosity, sludge, corrosive acids and poor engine efficiency, including reduced fuel economy. Oxidation takes place at the molecular level within the lubricant between the base oil and oxygen that exists in the form of entrained air or foam.

Oxidation can be controlled through more robust base oils with higher viscosity indices as well as anti-oxidants in an oil’s additive package. Anti-oxidants function in two ways: by delaying the onset of oxidation through the prevention of free radical formation and slowing the rate of oxidation by trapping radicals preventing crosslinking at the molecular level. Additionally, anti-oxidants suppress acid build-up that can lead to excessive engine wear.

A primary contributing factor to the most recent transition to API CK-4 was the requirement for a more robust oil formulation to protect against oxidation in modern diesel engines. In fact, the largest change from API CJ-4 to API CK-4 was focused around improved protection against oxidation. As part of API CK-4, the Volvo T-13 engine test was added. This test is designed to monitor an oil's ability to push the boundaries of oxidation stability in a turbocharged, intercooled diesel engine running on ultra-low sulfur diesel fuel to allow for extended drain intervals and improved bearing protection.

Oxidation levels are determined through Fourier-Transform Infrared Spectroscopy (FTIR) peak height increase (max of 125 abs/cm)[1] and an increase in kinematic viscosity at 40˚C (KV40) is analyzed at 300 to 360 hours of operation (at less than 75%). Measurements are taken and reported for the main bearings, piston rings and cylinder liners.

Through industry testing conducted as part of the transition to API CK-4, Archer Premium Arpeco exhibited a 45% improvement in oxidation stability over the specification limit (at 69 abs/cm vs. 125 abs/cm) and 7X better protection against increased viscosity (10.5% increase compared to 75%), as set forth in the Volvo T-13 test.

How did Archer Premium Arpeco perform on-the-road?

As part of the transition to API CK-4, field trials were conducted verifying Archer Premium Arpeco will perform in-the-field and over-the-road just as well as it performs on an engine test stand protecting against the negative effects of oxidation. The images and results below are from an overhaul conducted on a 2014 Cummins ISX 15.0 L engine after running Archer Premium Arpeco 500,000 miles with 50,000-mile oil drain intervals.

Main Bearings: Minimal corrosive wear is found on the upper and lower main bearings, with no appearance of lead, nickel or copper exposure, indicating these bearings are in excellent, re-usable condition.


Pistons: All pistons and piston rings showed no deposit build-up (and free-moving rings), ensuring optimum efficiency of the engine through proper ring seal within the cylinder liner for maintained horsepower, reduced blow-by and reduced oil consumption.

Cylinders: Minimal carbon deposits formed on the piston head, and cylinder honing (crosshatch to retain an adequate oil film) was very prevalent, proving this engine will maintain horsepower and torque.

How can you check for oxidation?

Contact your local Archer Lubricants distributor today and ask about Used Oil Analysis, which is included in your Archer Lubricants purchase. Used Oil Analysis is comparable to a human obtaining a blood sample and will help address an issue within an engine before the issue is critical. Additive levels of the oil will be checked, ensuring the anti-oxidancy of the oil is acceptable. Oxidation levels will be reported, along with any change in viscosity of the oil noted. Anything that is reported as “abnormal” or needs attention is reported immediately so a solution to protect your diesel investment can follow instantly.


[1] abs/cm = absorbance/centimeter. Absorbance is a measure of a quantity of light absorbed by a sample and is measured using spectroscopy (measures the interactions of molecules and related processes), particularly for quantitative analysis.