Direct Inject Motors
Direct Inject Motors were first introduced by BMW in 2005 on some models and are now the standard or automobile engine design. Direct inject does just what it says, it injects fuel directly into the cylinder combustion chamber instead of spraying a mist of gasoline in the air intake above the valves on the engine. Direct inject allows engines to perform at a higher combustion rate as well can deliver the fuel at a more precise time to the combustion chamber making engine more efficient and more powerful.
Direct inject delivers better fuel economy, more power, and reduced emissions. At Peak Auto we have found that direct inject motor have a few side effects including, carbon build-up on intake valves and higher oil consumption. The carbon that gets built up on the valves comes from the engine oil recirculating system called an oil separator, oil trap or PCV valve. This system recycles the hot oil gases that are formed by operating the vehicle. On vehicle engines without direct inject, the fuel injectors spray gasoline on the intake valves as part of the fuel delivery system. This action cleaned the valves and if you used a very good quality gasoline, such as Shell, then your valves would be kept very clean. With Direct inject you do not get this effect and the hot oil gas that is trying to be burnt to cut down on emissions leaves deposits of carbon on the valves. The new Pennzoil Euro Synthetic motor oil is cleaner and purer therefore has les dirt/carbon to deposit on the valves.
Higher oil consumption is caused by direct inject engine when the extra amount of compression that is made, forces piston ring blow-by of exhaust gases after combustion to enter the lubricant side of the engine. This mixture of the dirty exhaust gas will contaminate the clean consuming the additives in that oil. When the oil additives are depleted then sludge will start to build up in the engine, specifically on the piston rings allowing oil to escape and be consumed as well as more blow by. The new BMW Twin Power Turbo Motor oil or Pennzoil Euro Synthetic has a very robust additive package that is strong enough to combat the exhaust gases for the length of the oil change interval. Having said this, at Peak Auto located next to the Cary Auto Mall at 833 US 64 W in Apex NC, we strongly recommend changing your Mini Cooper engine oil every 5,000 miles. We have not found these motors to be very durable and the only hold 4 liters of oil.