Oil Life Monitoring Systems - Edmunds.com

Oil Life Monitoring Systems

New Technology Takes Guesswork out of Oil Change Intervals


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Until recently, the question of when to change your oil was usually answered by your local garage, which had a vested interest in servicing your car every 3,000 miles. Your alternative was to crack the owner's manual to see whether your driving habits fell into the "severe" or "normal" category. And then you'd let the listed interval be your frequency guide.

But increasingly, the change-interval question is being answered by a vehicle's oil life monitoring system, which signals the driver through the instrument panel. This alert usually arrives anywhere between 5,000 and 8,000 miles.

So how does the system know when it's time for a change? Electronic sensors throughout the drivetrain send information about engine revolutions, temperature and driving time to the car's computer. The data is run through a mathematical algorithm that predicts when the oil will begin to degrade. The light comes on well in advance, giving the owner time to get the car serviced.

Oil life monitoring systems have been around for several decades. They were introduced in General Motors vehicles in the late 1980s and have been phased in slowly, said Matt Snider, project engineer in GM's Fuels and Lubricants Group. "We are very confident in the accuracy of the system," he said. The average recommendation from the system for GM vehicles is 8,500 miles, Snider said. He said that the longest oil change interval he was personally aware of was 17,000 miles in a colleague's car. For 2010 vehicles, 14 of 35 manufacturers use oil life monitoring systems.

Real-World Evidence
The oil life monitoring system in a 2007 Honda Fit Sport owned by an Edmunds.com editor signaled for an oil change at 5,500 miles, due to a lot of around-town driving. Later, under highway conditions, the system (which Honda calls a "maintenance minder") came on at 7,600 miles. Clearly, the system had detected different driving conditions and adjusted accordingly.

When we had the oil changed, we captured a sample and sent it to Blackstone Laboratories. Showing the conservative nature of the oil life sensors, the analysis showed the oil had at least 2,000 miles of life left in it.

A long-term 2008 Pontiac G8 GT driven by Edmunds went 13,000 miles before the monitoring system indicated the need for an oil change. We also sent a sample of that oil to a lab for analysis. The result: The oil could actually have safely delivered at least another 2,000 miles of service. "With an oil life system, we can use the software to tailor an oil drain interval to the behavior of a certain customer," Snider said.

Freed From the Schedules
Perhaps the best thing about oil life monitoring systems is that they free car owners from the confusing exercise of slotting themselves in the normal or severe driving schedules listed in the owner's manual. Severe conditions are described differently by various carmakers, but some "severe" conditions that they frequently cite are driving in stop-and-go traffic, towing, excessive idling and driving in the mountains.

In many cases, quick-oil-change outlets and dealerships' service departments encourage frequent oil changes by claiming that every driver falls in the severe category. This begs the question: Why have a normal category at all? Oil life monitoring systems put an end to the debate by reacting to how you actually drive.

Using an Oil Life Monitoring System
If your car has an oil life monitoring system, read your owner's manual to get a feel for how it's going to communicate with you. In general, the systems are designed to be easily understood and used. Some systems will display the percentage of oil life left so you can schedule a service visit. The systems factor in plenty of extra time for the driver who procrastinates. For additional motivation, however, some systems will display a negative number to show just how overdue the oil change is.

When a technician changes the oil, he resets the monitoring system. Do-it-yourselfers can easily do the reset, too, just by using a series of commands found in the owner's manual.

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To find a dealership that knows how to treat shoppers right, please visit Edmunds.com's Dealer Ratings and Reviews.



  • Oil life monitor systems are changing the way vehicle owners decide when to take their car in for service, some of the changes are good, and some have the potential for serious trouble. The first thing that needs to be taken into consideration is whether the oil change service was performed with a fluid that meets the manufacturers specifications, and we are not just talking the SAE viscosity, there is a lot more to it than that. For the GM vehicles mentioned above, the bottle must display the dexos1 lable to be a licensed GM product and it doesn't matter what else someone might write on the outside of the bottle. Some companies will write statements like "Meets the engine protection requirements of dexos" but the dexos label is missing from the front of the bottle, which means the oil does not meet all of the requirements and should not be used. Dexos also does not require a "full synthetic", a group III base stock is capable of meeting the dexos requirements, however a group IV / groupV blend that meet dexos requirements would offer advantages and a greater margin of protection. Nearly every manufacturer today has vehicles that require oils that meet their proprietary specifications, when you check your owner’s manual you will see the API and ILSAC ratings such as 5W20, 5W30, 0W30 etc. GM's requirement normally looks like "Look for the API symbol and ILSAC starburst. Use an oil meeting SAE 5W30 and GM specification GM6094M". Now that is paraphrased here, but when you look in your manual it is usually in bold print immediately below the API donut, and ILSAC starburst. Today if your manual shows GM6094M, or GM4718M, they are both obsolete specifications and are replaced by dexos. The one video linked here shows the manual in the background and the GM4718M specification is clearly visible, that car today to be serviced correctly should get a dexos licensed product. Another common trap is the accidental resetting of the monitor system. GM publications specifically instruct owners to change their oil at 3000 miles if the system is accidently reset and no longer accurate. Some recommendations associated with this topic suggest sending an oil sample out for lab testing and yes you can definitely do that. Fleets do it all of the time in order to try and control expenses. But is that additional $25-$30 expense per test really justifiable for the average consumer? If you own and are maintaining one of the more expensive European models, and your oil changes cost around $100-$120 then maybe so. But if your vehicle can be serviced correctly for $29.00 you may not want to nearly double your expense. One of the biggest issues with the extended service intervals has to do with getting a technician to take a look at all of the other things that also need checked periodically. Many issues develop slowly over a period of time so the normal driver simply doesn't notice them until they finally create a situation that gets the drivers attention. One of the most accurate statements we ever hear is "I never noticed it before XXXXXXXX" some would allege that the problem occurred because of possibly something that happened while the vehicle was being serviced, however most of the time the gradual nature of most failures allows them to be ignored until the owner has a reason to pay closer attention to their vehicle, then they notice XXXXXXX. When a real technician has your vehicle in for service, even if it's a visit for one of the most minor issues it should still get a look over, and all of the other fluid levels checked, and then above all a road test even if it's just around the block. The tendency for many owners to take their vehicles to quick lubes causes them to lose the chance for the kind of attention to detail and disciplined approach to properly inspecting their car that only a true master technician can deliver. Now with the fact that cars can go a year or more between even one of the most basic services has many vehicles being neglected. This is resulting in breakdowns, and greater failures than the owners would otherwise have had to deal with. It's also contributing to a situation where there are fewer places that can handle the larger problems that can occur which means sudden breakdowns can lead to a longer period of time without your car. Today there is so much more to know, and it’s all driven by the technology that is in the industry. Things like what are the ACEA ratings and are they important for choosing the correct oil for your car? Is there really a difference between synthetic, fully synthetic, advanced synthetic, synthetic blend, and other oils without those words on the bottle? What does it mean when a bottle of oil that is labeled synthetic says on the bottle that it cannot be sold outside of the Americas?

  • tqmsystems tqmsystems Posts:

    In the one video, your engineer mentions you can switch from conventional oil to synthetic or back anytime. You may want to caution people that some engines and transmissions now require synthetic oils and using conventional oils may void the warranty.

  • FYI: Vehicles equipped with oil life monitors can not tell the difference in the oil ( conventional petroleum or synthetic ) quality you are using.

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