Should you trust oil life monitors or not?
Most automotive technicians will say "no way" if you ask them if they trust an oil life monitor.
All of the manufacturers equip their models with some form of OLM.There are two questions that come up: can an OLM light or system accurately tell a customer when they need an oil change?
There are a lot of variables that need to be considered, and both the customers and service technicians must be involved.The operator's manual must be followed along with the proper engine oil and level.
The 3,000-mile oil change service interval has been rendered obsolete due to the constant improvement in engine technology, manufacturing processes, engine management systems and other factors.The modern engine oil Additive package prevents sludge and varnish formation, and protects against engine wear and loss of engine performance longer than previous oils, even under increasingly severe engine operating environments.
Many of the original equipment manufacturers recommend oil change intervals of 5,000 to 8,000 miles.When it comes to a required oil change, combining these advances in technology with an OLM helps to remove some of the guesswork and concerns that a driver was previously faced with.
Today's best engine oil has a fixed lifetime and will need to be replaced or maintained periodically to ensure the safety, longevity and reliable performance that customers demand from their vehicles.It seems that maintaining a vehicle is not a priority for the busy public.
Increasing the oil change interval is something drivers want.Reducing vehicle down-time and decreasing operating costs is something the manufacturer can promote.It prevents the draining of oil that hasn't reached the end of its service life.
The owner's manual will recommend oil changes.A vast number of different driving conditions and other variables that affect oil life and engine performance will be considered when creating an effective timetable that will call for maintenance before signs of engine wear occur.
The owner's manual will lead to a generalization of when an oil change is needed.The owner's manual should be followed closely.The owner's manual may state that an 8,000-mile oil change interval is ok under normal or ideal operating conditions.What are the ideal operating conditions?How will non-ideal operating conditions affect the oil in the engine?
Many drivers think that their vehicles operate under ideal conditions, and thus justifying extended service intervals, when in fact they are operating under severe conditions and need more frequent oil changes.The severe category includes stop-and-go driving, frequent short trips, very cold or very hot weather.
The confusion starts when vehicles operate in a mix of conditions.The OLM is supposed to eliminate this confusion.Many factors can shorten the oil change interval.These are not limited to:
These scenarios contribute to oilcontamination from water, fuel, dirt, excessive blow-by gases, corrosive acid forming agents, oil oxidation, sludge, volatility issues, and a host of other issues which all tend to shorten a required oil.
Today's engine management systems keep fuel control as close to the ground as possible.oxidation stability, thermal constancy and shear stability are provided by synthetic lubricants.The amount of wear and foreign materials in the engine oil is limited by the superior quality oil filters.
Highway operation allows the engine to reach operating temperature at a reducedrpm, vaporizing any water and fuel in the oil, and it also lowers the operating hours per mile traveled.Reducing the impact of the waste oil that is created is a crucial factor, not just for the environment but for consumers and manufacturers alike.
The oil change service interval can be adjusted with the use of an OLM.
Each version of OLM has its own operational characteristics.The factors that can affect the engine oil life in both a positive and negative way can be taken into account by some OLMAs.
This is the most basic form.The OLM tracks the distance driven since the last oil change.A message reminder is illuminated when the preset distance is reached, warning the driver that an oil change is due.This system is used by manufacturers such as Honda and Toyota.
Each time the ignition is turned on, the service in miles will be displayed by the system.This style OLM keeps track of the distance since it was reset, and negative miles will also be tracked once it reaches zero.The message to the driver will be displayed after the system reaches zero.
The OLM does not take driving factors into account.Factors that affect oil life are not taken into account with this system.
The OLM light may not be effective at predicting the wear conditions of the oil in both a positive and a negative way.
Heavy, hard, hot-driven vehicles towing a trailer may not get the oil change that is needed soon enough and lightly driven vehicles may get their oil changed too often.
This style of OLM relies heavily on the vehicle operator to ensure that the oil level is maintained at the correct level, and to check the suggested service intervals in the owner's manual, because of the lack of sophistication.
The software-based style of OLM uses complex math to better predict when the engine oil will need to be changed.The system tracks how the vehicle is being operated.
GM started using this type of OLM back in 1998 and based the need for an oil change on the number of engine revolutions and operating temperature.
Normal flowing highway, high temperature/high load situations, city driving/ short trips and cold starts are the classifications that GM decided on.
Engine oil degrades based on oil temperature.In the first three operational categories, oil wear was related to operating temperature and that extreme short trips generated enough water and oil contaminates to cause the oil to degrade.
The software will adjust the oil change interval based on operational characteristics, climate conditions and driving habits.
The Ford system has a timer that will turn on the oil change required light after a year, but the software-based IOLM is very similar to the GMOLS.The amount of ethanol in the fuel being used is calculated by using the software-based method.
The correct oil is installed, the proper oil level is maintained and the OLM system is reset after an oil change.
Most manufacturers agree that engine oil degradation is influenced by temperature.
VW/Audi uses an OLM that calculates the engine oil's thermal load using an oil level/temperature sensor in combination with a fuel consumption and mileage/time algorithm to calculate when anoil change is necessary.GM and Ford use fully software-based systems that measure the amount of oil and its temperature in the crankcase while the engine is running.When the engine oil level drops below the full mark, this style of OLM can take into account the accelerated wear that occurs to the oil and its package.
The standard oil that was installed in the engines was changed to a more robust synthetic oil to enable an extended service interval.
Measuring the distance, using a software-based algorithm and monitoring the oil's temperature and level are all good ways of extending an oil change interval, but they all have one problem: They can't directly measure the condition of the engines oil.
The actual engine oil condition sensor was developed.The oil condition sensors take advantage of the fact that the dielectric properties of engine oil change as it wears out.
As the oil's acidity increases, the sensors can be used to detect engine coolant or fuel.
Mercedes-Benz takes advantage of an oil condition sensor in its Flexible Service System to extend the oil change intervals.BMW uses a similar sensor to evaluate the condition of the engine oil on their models.
If the proper oil is installed, the oil condition sensor will allow for up to two years and 15,000 miles of service.
When an oil sensor is combined with operating condition data and oil level, the extended service interval can be reached but only if the correct oil is installed and the level is maintained.
Some OLM systems can measure the oil's condition, but they can't compensate for sub-standard engine oil or oil that does not meet the minimum preference standards set out by the original equipment manufacturer.
When an inferior engine oil reaches the end of its life, it may oxidize, form engine deposits and sludge, all while the OLM indicates substantial remaining life.
Engine wear can be accelerated by engine degradation oil.Driving conditions are one of the major factors.
Most of these operating conditions will fall under the severe service definition in the owner's manual, something that needs to be considered with some forms of OLM, especially the simpler mileage counter style.
When used in conjunction with an engine oil that meets or exceeds the manufacturer's recommendations, the OLM can be trusted.Analytical oil tests and research have been done by the OEMs.
Even at the maximum drain interval, the engine oil will still meet all requirements.
The benefits of extended oil change intervals include less frequent service requirements, less down time, reduced operating costs, and more eco-friendly operation due to less waste oil and superior filters.
The use of an oil condition sensor and oil level sensor has eliminated the need for a dipstick on some vehicles, something that symbolizes the fact that fewer people are opening their hoods to inspect the engine'soil level.
We will likely see the intervals grow longer as the oil service interval is a fact of life.If an oil change will increase, the price will go up.
Engine technology, oil filters, and engine design are all continually improving.As the OLM decides how the engine oil degrades, it will take these and other factors into account.
The amount of oil in the engine has been increased to compensate for longer service intervals.A Chevrolet Silverado with a 5.3 V8 now holds 8 quarts of 0W20, an increase from the 6 quarts it held in the previous model.The correct oil level is maintained throughout the service interval and is dependent on the proper manufacturer-specific engine oil being installed during an oil change.The OLM system can't function if neither of the requirements are met.
I would like to thank Sean Lantz for his contributions to the article.
Jeff Taylor has been in the automotive industry for 34 years and is a fully licensed professional lead technician.While still on the bench, Jeff is heavily involved in government focus groups, serves as an accomplished technical writer and has competed in international diagnostic contests as well as providing his expertise as a automotive technical instructor for a major aftermarket parts retailer.