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Engines today are more powerful and efficient than ever. Their complexity is being driven by decreased emission output and increasing fuel economy standards. As a result new technologies had to be developed and implemented to meet these stringent standards.
With these new technologies the engine lubrication system had to advance as well as the quality of the oils to keep these new systems properly lubricated. I will go over a few of these technologies that have impacted engine design.
The first is GDI or Gasoline Direct Injection. This new fuel system technology has changed the way fuel is delivered to the engine by directly injecting it into the cylinders at a very high pressure and not at the back of the intake valves with older designs you may have seen in gasoline or fuel system additive commercials on TV. Since fuel is not being injected at the back of the intake valves they may build up with carbon that will restrict airflow to the engine and cause performance issues. Using the correct oils for these engines will reduce the the amount of buildup but won’t eliminate it completely. Induction system cleaning by chemical fogging regularly will reduce the buildup as a maintenance service. Severe cases may require cylinder head removal. Also part of the GDI system is the high pressure mechanical pump that is driven usually by a camshaft. You still have an electric powered medium pressure feeder pump inside the fuel tank that provides the high pressure pump with fuel. The high pressure pump operates in the 200 – 3000 PSI range so the contact area between it’s pump shaft and the camshaft has to have clean oil that meets the engines requirements to reduce wear.
Second, is Variable Camshaft Timing Systems and Timing Chain components. The variable camshaft components are controlled with engine oil pressure through computer controlled solenoids that control camshaft position for optimum engine performance and economy. If the oil is not changed regularly, sludge will form and potentially stick in these solenoids and camshaft timing components, causing rough running, stalling and check engine lights to be illuminated.
There are other systems that can be affected by improper oils and maintenance but the last one I will touch on is computer controlled oil pumps. Previous designed pumps were mainly controlled by engine rpm. With this system there were several operating modes that didn’t require full pressure or volume. Knowing this, the engineers designed a way to regulate the operation of the oil pump to reduce pressure and volume. This in turn would reduce engine load and save fuel. This is achieved by the use of a computer controlled solenoid that moves oil pump components that could be affected by the wrong oil or not changing it when needed. You may have a check engine light illuminate if the computer is not able to achieve the correct oil pressure according to look up tables for a certain temperature, engine rpm and solenoid command. Engines have changed.
Current oils required by manufacturers vary greatly by engine type, capabilities and design. By and large, engine tolerances and clearances between components have been reduced requiring lower viscosity oils. Viscosity is explained as resistance to flow. Engine oil is rated for cold and warm viscosity ranges and engine manufacturers will recommend a different oil viscosity rating for certain climates. If your commute involves sitting in constant stop and go conditions, pull a trailer, drive in dusty conditions or drive aggressively you are a candidate for using the severe service maintenance schedule in your owners manual. The longer an oil is operated in an engine the higher the viscosity will increase unless it’s being diluted by fuel or antifreeze entering the crankcase. If it’s not changed in a recommended interval, it’s viscosity rating may rise to an unsafe level for the operating range of the engine. Additives are also added to guard against the remaining acids of the combustion process from piston and ring wear or oxidation reducing it’s lubrication properties. As engines age and wear it’s more important to keep the engine oil serviced with the recommended oil and a quality oil filter.
I hope this has given you some insight to the engines of today and their oil requirements. As always please feel free to contact us with any concerns regarding your vehicle’s maintenance, repairs or operation.
Kevin Hough, ASE Certified Master and L1 Advanced Level Specialist