LUBGARD SUPER DIESEL PLUS API CI4/SL is today’s technology trend of diesel engine is towards more environment-conscious products with less gas emission and longer overhaul period. Coming along with these development, new devices like the Exhaust Gas Recirculation(EGR) rely much more on the performance of the engine oil being used. LUBGARD SUPER DIESEL PLUS API CI4/SL, the newest version of the CI4/SL series high-performance heavy diesel engine oil, is well positioned to address those needs.