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Today engine technology requires a lubricant of higher performance due to longer drain intervals, higher temperature and improved after-treatment durability and fuel economy. To meet those new requirements, new oil formulations are using more and more hydrocracked and synthetic base oils together with new additive package. We can therefore wonder how this will impact on the Life Cycle Assessment of those lubricants whose objective remains to lubricate engines during a certain period of time. The results of this study will show that LCA is the only way to fully evaluate environmental impacts of a lubricant. In our study, we will see that a synthetic lubricant produces more Greenhouse Gases (GHG) during its production stage while during its use on the car the tendency will be inverted.

An investigation into applying a tracer gas method for determining trapping efficiency to 4-stroke engines is carried out. The experimental errors are identified and analyzed. The errors include incomplete cylinder reaction, exhaust instability, and inconsistent exhaust sampling. Tracer gas global kinetic mechanisms are reviewed and used as a means for tracer gas selection. The tracer gases investigated are nitrous oxide (N2O) and monomethylamine (CH3NH2). As a benchmark the oxygen tracer technique is analyzed, where oxygen is used as the tracer. Test results from a GM 5.7 l, 8 cylinder, 4-stroke engine are presented that include measurement of the experimental errors and the trapping efficiency. Of the tracers considered, N2O is determined to be optimal for the engine tested.