March 19, 2018

When should engine oils be changed?

by fluidlife in Fluid Insights, Oil Analysis

Mark Shierman, Corporate Director, Client Services, Fluid Life

Passenger car drivers are presented with multiple messages about when to change engine oil. Oil change recommendations may vary between the dealer, owners manual, and built-in engine oil life monitors. It is important for consumers to understand the underlying reasons behind each recommendation, and to select an oil change frequency that fits their needs.

The automotive industry has readily adopted the use of built-in engine oil life monitors, first introduced around 1986. Not all passenger cars include these devices, but more and more vehicles include them every year. These oil life monitors do not actually monitor the oil condition, but rather use an algorithm to model the expected oil life. They keep track of the number of engine revolutions since the last oil change. They apply an algorithm to determine when the oil should be changed, and make adjustments based on various vehicle operating conditions. Changing the oil based on the vehicles’ oil life monitor is the best way of changing the oil safely. However, it is important for the car manufacturers to provide guidance on vehicles that aren’t equipped with these devices, or to consumers who don’t wish to follow these recommendations for whatever reason (irregular usage, personal bias, cost constraints, etc.)

Owner’s manuals typically suggest the minimum amount of maintenance that should be performed to keep the vehicle operating as expected, and to maintain warranty coverage. Consumers are not required to follow these instructions, but may be denied a warranty claim if the lack of maintenance is suspected as the cause of the issue. Warranty compliance is not typically a concern on older vehicles past the warranty period. The language contained in owner’s manuals is usually written very carefully. Recommendations usually suggest changing the oil based on the vehicle’s on board oil life monitor, and only changing the oil at their suggested frequency if the oil life monitor has not indicated a need to change the oil previously.

Dealer recommendations typically follow the owner’s manual as a starting point, but they also try to take into consideration other factors:

a) Is the vehicle equipped with an engine oil life monitor (if so, they will defer to those recommendations for when the oil should be changed).
b) Does other maintenance need to be performed (oil changes should be scheduled along with other important maintenance items such as tire rotations, fluid level checks, brake inspections, oil changes on other compartments, etc.)

Dealers often send email notifications to their customers as a matter of convenience. Because dealers cannot know for certain how many kilometers have been driven in that time period, they generally just send out maintenance reminders every 3-4 months. These are intended to prompt consumers to check whether or not they do actually need service. These email reminders provide a similar function as the oil change stickers that would be applied to the vehicle’s window. Ultimately, dealer recommendations are used to provide their customers with a reasonable amount of reliability and convenience.

Oil analysis is typically performed by the car manufacturers when they initially develop their engine oil monitor algorithms. Consumers don’t tend to use oil analysis very often, unless they are considering changing their oil change habits significantly. Oil analysis can be very helpful in these situations, but may require some expertise to properly diagnose the test results.

Car manufacturers recognize that everyone’s driving patterns are unique, and have done a great job at developing technology (engine oil life monitors) that takes this into consideration, and gives everyone a tailor-made answer to the question of when should the oil be changed. Dealers do a great job of reminding consumers when an oil change is coming due, and making this process convenient for the consumer. In order to accommodate all consumers, the dealer recommendations are inherently conservative. Consumers that follow these suggestions often experience fewer problems, and have vehicles that can remain in service for longer periods of time.

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