Advanced science.  Applied technology.


Elucidating the Link Between Lubricant Composition, Piston Location, and Scuffing in the DD13 Engine, 08-R8791

Principal Investigators
Jose Starling
Inclusive Dates 
01/01/17 to 01/08/18


The DD13 (Detroit Diesel 12.8L in-line six heavy-duty diesel engine) scuffing test was developed to address an issue occurring during engine durability testing at Detroit Diesel (Daimler) which was leading to scuffing events. The test development continued over the past few years and was approved as an ASTM procedure in December 2016 (ASTM D8074, Standard Test Method for Evaluation of Diesel Engine Oils in DD13 Diesel Engine). While the procedure has been finalized and is a formal method, there is still a considerable level of uncertainty as to what is causing the scuffing event and how or where it starts in the engine. The test itself has a high degree of variability in terms of when scuffing occurs, even in cases where the oil formulation is unchanged. This uncertainty is driving the need, by oil and additive companies, to further understand the test.

It is now commonly accepted that the oil in the piston assembly is significantly different than the oil in the sump, being more highly degraded and with higher fuel dilution. The goal of this work is to sample the oil from various locations on the piston and conduct analyses to quantify changes in the chemical and physical properties of the oil over time. This information yielded a deeper understanding of the test for SwRI staff and resulted in a technique that we can market to oil and additive companies.


The objective was to sample oil from the second piston land and top and second ring groove. Although very close in proximity, these three regions are expected to have significantly different lubricant properties due to localized temperature differences, oil degradation rates, oil flow rates, blowby gas concentrations, and fuel dilution. Chemical analysis of these sampled oils can elucidate the lubricant properties in these localized regions. It is believed that the scuffing events most likely occur between the top piston ring face and the cylinder liner. The DD13 engine test has been modified to use non-coated top rings to increase the ease with which the two parts scuff. Understanding the tribological effects of the lubricant properties on the ring liner interface is paramount for understanding the scuffing mechanism.


At the end of this project sufficient progress had been made such that additional client funding was provided to continue the work. Currently, the engine is running and reliably sampling oil from all locations. In addition, a presentation titled “DD13 Scuffing Test – Tribological and Chemical Analysis of Ring Pack Lubricants” was presented at the STLE 73rd Annual Meeting and Exhibition in May 2018.