Selecting the right maintenance schedule is imperative for the health of the engine in preventing major engine repairs or in extreme cases preventing a total engine replacement. Neglecting the required service interval can result in an accumulation of sludge and deposits that can restrict the flow of lubricant to vital engine components.
Consider the following:
1) The accumulation of sludge/debris in the oil pan can block the oil pump pick-up tube.
2) Valve cover breather ports and oil return ports can become restricted.
3) Rocker arms and valve covers become coated with sludge.
4) Lubrication to the camshaft actuator solenoids becomes restricted.
5) Inoperative active fuel management valve lifters/solenoids.
6) Under or over pressurization events resulting from the pressure regulating valve in the oil pump sticking.
7) When performing a lube service, check for the presence of sludge in the oil filter pleats, oil filter cap and the filter element for splits or tears (see illustration).
8) Damage due to the contamination described will not be covered by the vehicle manufacturer’s warranty.
Illustration Courtesy of GM
If the oil filter and filter cap reflect this level of sludge accumulation, the oil pan, pick-up screen, cylinder heads, camshafts and related valve train components will likely contain this same level of sludge deposits.
Technicians that have been in the service business for thirty plus years sometimes have difficulty in accepting extended service intervals, as most were accustomed to a full service every 2500 miles. Driving a vehicle according to today’s extended service intervals was not a consideration for them. New engine technology, filtration and lubricants have made the internal combustion engine more fuel efficient, cleaner and less polluting, making these new recommended service intervals possible.
Fluid levels are another concern as full-service stations that kept a watchful eye on fluid levels are a thing of the past. Most vehicle owners never check the fluid level unless a lamp in the instrument cluster is illuminated and often that means it is too late, as the damage is often already done. If the vehicle was not equipped with a service reminder lamp, many would operate their vehicle far beyond the vehicle manufacturer’s recommended service interval. When this occurs, bad things can happen, resulting in major expensive repairs.
Many vehicle owners have difficulty in identifying the proper service interval, which is determined by the vehicle operating conditions. Unfortunately, many assume they drive under normal service conditions when severe service is usually the case. Consider the following:
Normal Service…This service schedule involves a vehicle that is continuously driven at constant highway speeds. During these driving conditions the engine operates efficiently, thereby reducing crankcase dilution that can result in accelerated engine component wear.
Severe Service…Most are surprised to learn that their vehicle should be maintained at a severe service level. Following are some conditions that qualify the vehicle under a severe service category:
1) Short trip driven vehicles (5 miles or less) promote an accumulation of sludge and other deposits due to the oil not reaching its normal operating temperature, which can burn off condensation and other contaminants. Crankcase dilution occurs when the engine is not operating efficiently.
2) Vehicles driven during extreme hot weather conditions, especially in heavy or stop and go traffic.
3) Vehicles driven 10 miles or less in ambient temperatures below freezing.
4) Taxis or delivery vehicles driven at slow speeds for long distances such as that encountered during heavy traffic
conditions. Vehicles that are allowed to idle for extended periods of time, such as that of law enforcement.
5) Vehicles driven off-road in dusty conditions.
6) Rough, muddy, sandy, or salt spread road conditions.
7) Driving continuously while exceeding normal highway speeds.
8) Pulling a boat, trailer or camper.
9) Frequent starts and stops.
Bearing clearances and the composition of the metal used in the bearings, plus changes in engine technology require different lubrication and filtration characteristics. The vehicle manufacturer’s recommended oil viscosity is imperative. Filtration is another concern as there is more to filtration efficiency than the physical characteristics and dimensions of the filter. Filters of equal size often share different efficiency and capacity ratings. The selection of a filter for a given application varies depending on the media, porosity of the media, surface area and its total capacity, plus the bypass valve setting. Design changes in engine and lubrication technology have resulted in an increase in the oil flow rate, resulting in a higher engine pressure differential across the filter media. These changes prompt an increase in the filter bypass settings to prevent unfiltered oil from flowing to and through the vital engine components, resulting in accelerated bearing wear and component failure.
The presence of any minute substance such as sludge contamination or flakes of metal has the potential to stick the pressure regulating valve in the oil pump. When this occurs, the result is a high or no oil pressure condition depending on the position of the valve. Stuck open, results in a loss of oil pressure. Stuck closed, results in over-pressurization. The following are some conditions that can promote pressurization symptoms.
1) Plunger or bore wear in the oil pump.
2) Imperfection in the regulating valve bore.
3) Sludge deposits due to poor maintenance.
4) The presence of any foreign debris can restrict valve movement.
5) Metal fragments from bearing wear or machining.
6) Gasket removal with an abrasive disc produces fine grit that the oil filter may be unable to remove.
7) Improper lube viscosity promoting bearing or component wear.
8) Damaged or improperly sealed air filter.
ENGINE REPLACEMENT GUIDELINES
GM advises that an engine failure due to damaged rod or main bearings may result in debris from the bearings passing directly through the oil galleries and other components that are a part of the lubrication circuit. It is difficult to ensure these passages are completely clean. Contamination from the failed components can transfer to the new engine causing damage or engine failure.
If equipped, the oil cooler, oil cooler lines, oil tank and turbocharger will require replacement due to the complex oil gallery passages, making it difficult or impossible to determine if all debris has been removed. On some vehicles the oil cooler is a part of the radiator, requiring replacement of the radiator. GM states that not every engine that encounters bearing damage will require replacement of the mentioned components. They offer guidelines and illustrations to make the determination in GM Service Bulletin #18-NA-073.
Summary: Identifying and maintaining the correct service interval for the application and operating conditions is imperative for the health of the engine.
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