Top Tier gasoline, and Factory recommended engine oil – helps reduce the infamous “carbon build up” on the backsides of the intake valves on direct fuel injection engines caused by the effect of “exhaust gas recirculation” (EGR) and positive crankcase ventilation (PCV).
EGR is an emission system that meters exhaust gas back to the engine cylinders thru the intake cycle via either a valve or by a designed “valve train” using “valve overlap”.
This process lowers combustion temperatures in the cylinders that help reduce levels of Oxides of Nitrogen.
The PCV system routes crankcase pressure (that is formed by the air being compressed in the cylinder leaking past the sealing rings of the piston into the oil pan / crankcase) into the intake system where it mixes with fresh air and drawn into the combustion chamber via the intake cycle.
So a cleaner burning fuel along with factory spec oil & fill capacity will result in less formation of carbon in the exhaust gas and crankcase vapors which boasts a lesser effect of carbon buildup on the backsides of the intake valves of these direct injection engines.
For more information on Top Tier Gasoline and who sells it check this website: TopTierGas.com