Why is a scuffing test proposed for future heavy-duty diesel engine oil performance categories?
Heavy-duty diesel engine builders are interested in improving fuel efficiency (FE) and lowering green-house gases (GHG) due to environmental regulations on clean air and customer pressure to lower the cost of operation. As a result in the PC-11 heavy-duty diesel engine oil performance category currently under development the EMA has proposed introducing lower viscosity oils that can improve FE and reduce GHG. Evidence indicates that lower high temperature high shear (HTHS) viscosity can reduce viscose drag within the engine from the engine oil and reduce the amount of fuel consumed. However, low HTHS oils may cause excessive wear in engines not designed to run on these lower viscosity oils. Click here to learn more about HTHS.
Daimler is leading the development of the PC-11 scuffing test with assistance from Lubrizol. Click here to link to the Daimler presentation of 12/6/11. No engine tests in API CJ-4, the current heavy-duty diesel engine oil performance category, addresses adhesive (scuffing) wear. Adhesive wear occurs when metal to metal contact forces are high enough to cause metal transfer from cold welding and tearing. Adhesive wear often occurs during break-in as the surface asperities wear off and is more likely as HTHS viscosity decreases
In North America, Europe, Japan, and soon Brazil, heavy highway diesel engine particulate matter emissions regulations force the use of diesel particulate filters (DPFs) to trap and oxidize carbon soot in the exhaust. Installation of DPFs allowed diesel builders to retune engines (more specifically, to adjust fuel injection events) to achieve cooler combustion which reduces the formation of harmful nitrous oxides (NOx) but at the expense of boosting output of unburned...