TOP TIER™ Performance Standards

TOP TIER+ Gasoline Performance Standard
The TOP TIER+™ Gasoline Performance Standard will extend the current benefits to newer, higher-efficiency gasoline direct-injected (GDI) engines. The new Plus gasoline standard will include a GDI Fuel Injector Cleanliness Engine Dynamometer Test while monitoring for optimal emissions and combustion behavior.

TOP TIER+ Diesel Performance Standard
The TOP TIER+™ Approved Diesel Performance Standard adds enhanced wear protection for modern high-pressure fuel injection hardware systems and greater fuel storage stability performance on top of the base-level features of detergency and cleanliness performance.
Gasoline Base Performance Standard
The TOP TIER™ Detergent Gasoline Deposit Control Performance Standard describes the test methods used and the performance requirements that retail unleaded gasoline must meet to be licensed as TOP TIER™.
Diesel Base Performance Standard
Today's TOP TIER™ Diesel Fuel Performance Standard has been streamlined into two levels of performance requirements for greater market flexibility and has been revised to focus on detergency and contamination cleanliness requirements.