27 September 2011

Acting on a request by the Engine Manufacturers Association (EMA), the American Petroleum Institute (API) and Diesel Engine Oil Advisory Panel (DEOAP) have initiated the development of a new heavy-duty diesel engine oil performance category: PC-11 (PC stands for “proposed category”) that will offer performance features beyond the current API CJ-4 engine oils. The formal written request, dated June 21, 2011, proposes first licensing by API no later than January 1, 2016.

The EMA request has been driven primarily by the recently adopted EPA/NHTSA fuel economy and greenhouse gas emission regulations for heavy-duty trucks. Engine lubricant performance can have a significant influence on an engine’s ability to achieve EPA’s fuel efficiency goals, said the EMA. The fuel efficiency effect of heavy-duty engine oils is directly related to high-temperature/high-shear (HTHS) performance; however, many engines require the current HTHS level of performance to achieve acceptable engine durability. Therefore, EMA requested that the PC-11 category be split into two separate subcategories with corresponding HTHS performance levels: one that preserves historical heavy-duty oil criteria, and one that provides fuel efficiency benefits.

In addition to the EPA/NHTSA fuel efficiency requirements, the need for PC-11 is driven by:

  • Increased use of biodiesel fuel
  • Engine oil foaming concerns
  • Improved protection from higher engine operating temperatures
  • Improved protection from engine oil shear down
  • Piston/liner (adhesive) wear protection

The EMA proposal suggests the following performance parameters be addressed in PC-11 oils:

  • Fuel efficiency contribution from the engine oil
  • Biodiesel fuel compatibility/protection
  • Improved engine protection from aeration
  • Improved oxidation performance
  • Engine oil shear stability protection
  • Improved scuffing wear protection

Source: The Lubrizol Corporation