https://crcao.org/reports/recentstudies2018/AVFL-28/CRC%20AVFL-28_Final%20Report_JAN2018.pdf
The trends in the wear rates sure are complicated and don’t follow simple rules. Start-stop wear is particularly significant and is worse for the 0W-16 oil than the 5W-30 oil. Be sure to check out the graphs and the photos in the appendix.
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ABSTRACT
Existing engine lubrication wear tests based on ILSAC and ACEA specifications were developed for engines and operating conditions representative of port fuel injection (PFI) engine technology. The automotive industry is trending away from the PFI engine towards gasoline direct injection (GDI) technology with approximately 40 percent of passenger cars sold in 2014 having GDI engines, many of which are turbo-charged. These turbo-charged GDI engines often produce more severe operating conditions than PFI engines due to their higher operating temperatures, cylinder pressures, and specific torques. In addition, most turbo GDI engines are downsized, therefore operating at higher loads for a greater portion of their operating cycle. Some vehicles use alternative combustion cycles or stop-start technology which further subjects the engine and lubricants to higher levels of stress compared to conventional PFI engines.
In an effort to guide the development of engine lubrication wear tests in the next ILSAC and ACEA categories, the rings, liner and rod bearings of a modern turbo charged GDI engine, a Ford 2.0L Ecoboost engine, were irradiated and the engine assembled and placed on a test stand. The irradiation of these engine components resulted in the formation of different isotopes, depending on the component material. A series of in-field operating conditions were selected and the engine operated at these conditions using both a SAE 5W-30 oil and a SAE 0W-16 oil with the same additive package. Using the SwRI® Radioactive Tracer Technology (RATT®) the level of radioactive particles in the oil, present due to wear of the irradiated engine components, can be detected and the strength of the signal for each isotope can be correlated with the mass of wear material in the oil.
Results showed no measureable wear in the connecting rod bearings, higher wear response from transient than steady state engine operating conditions, noticeably higher wear during stop-start and roughly only two thirds of the operating conditions resulted in higher wear in the measured engine components using SAE 0W-16 oil over SAE 5W-30 oil.
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CONCLUSIONS
A project was undertaken to investigate the wear of rings, liner and connecting rod bearings in a Ford 2.0L Ecoboost engine using Radioactive Tracer Technology® to track real time wear of the components individually. The results clearly show the operating cycles that created significant wear in the irradiated engine components.
A significant amount of data was produced for the five irradiated engine components across the engine operating test matrix. The main findings are:
• After initial run-in, no measurable wear was recorded for the connecting rod bearings
SwRI Final Report, Project No. 08-22469 Page 14 of 15
Comparing the wear rates using SAE 5W-30 and SAE 0W-16 oils, lower viscosity lubricant resulted in higher wear across roughly two thirds of the engine operating conditions
• In general, transient engine operating conditions created higher wear than steady state conditions
• The stop-start cycles produced some of the most significant difference in wear rates for the two lubricants and often the highest wear rates recorded
• The cold start cycles operated at the beginning of every day of testing did not exhibit appreciable wear rates on any of the irradiated components
• It is intuitive that higher load would result in higher wear between the ring face and liner. However, the results of this work show that not to be entirely accurate, with only transient speeds at high load giving significant top ting face, top ring side and liner wear. The WOT 3500 at maximum boost only produced significant wear on the top ring side when running with SAE 0W-16 oil.
Once again only time will tell.
