Oil Change: What is the best maintenance interval?

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By Jim Marotta

Update: This article was first published in 2011. Changing your oil too frequently hurts the environment but has no impact on your vehicle’s efficiency. Due to advancements in vehicle and oil technologies, your vehicle may be able to go longer between oil changes without compromising your vehicle’s engine or sacrificing performance.

The 3,000 mile oil and filter change is as much a part of the American car culture as hot rods, car hops and whitewall tires. Whether we perform it ourselves in the driveway or watch while the family “mechanic” puts the car up on the lift and drains the oil, we think of the 3,000 mile number as the standard interval for oil change service. But, look at a maintenance interval chart; manufacturers are gradually extending service intervals.

Oil Change: What is the best maintenance interval?

What is the best interval for an oil change? Manufacturers are extending service intervals. Photo by Jim Marotta.

The move toward extended service intervals coincides with new oil technologies that allow manufacturers and refiners to create more stable oils that will endure longer service, and a decrease in the frequency of other services such as tune-ups.

Conventional vs. Synthetic

Traditionally, manufacturers made conventional engine oils from a mineral base oil stock derived from crude oil. Synthetic base oil stocks are produced by either highly processing and refining mineral based oil stock, or by chemically engineering synthetic base oil stock. Current additive packages blended into conventional oils allow them to function longer than oils of the past, but it is primarily the synthetic base stocks that allow greatly extended intervals.

Synthetic oil offers many advantages in durability versus conventional petroleum oil and it is all based on the synthetic oil’s superior resistance to heat and oxidation while requiring little or no viscosity index improvements which are the most vulnerable to degradation as oil ages. Synthetic oil is more accurately controlled at the molecular level and therefore can be engineered to resist the forces in an engine that work against oil durability.

How Long Does Engine Oil Last?

Clearly there is a degree of ambiguity about how long motor oil actually lasts. Traditionally vehicle owners have felt more comfortable with convenient mileage or time-based schedules while others prefer seasonal changes, but the question still remains – how long does engine oil last?

Many factors contribute to the degradation of motor oil. Extreme heat breaks down oil molecules which evaporate and leave deposits on internal engine surfaces, inhibiting the transfer of engine heat to the oil. Oxidation, which is accelerated by heat, further inhibits heat transfer. Environmental contaminants such as dust and dirt enter the engine through improperly maintained filters, and normal engine wear produces metallic particles that travel through the engine increasing wear. Byproducts of normal combustion – soot, dirt, and sludge – contaminate the oil and change viscosity. Finally, internal pressure breaks down the oil film between moving parts which agitate the oil, trapping and suspending air and promoting oxidation.

Lubricant manufacturers continually research and experiment with various chemical additives that in some cases comprise 20 percent of a typical multi-grade oil. In addition to viscosity index improvements, which are the primary additives that allow for multi-grade oils, manufacturers use rust and corrosion inhibitors to neutralize acidic oxidation of the oil. Manufacturers use detergents and dispersants to minimize sludge buildup, along with anti-foaming agents and pressure additives to prevent oil barrier breakdown between internal engine parts. This is known as the shear factor. Manufacturers use additives to aid the base oil in the protection of engine components, but each has limitations and can be affected by the same factors that degrade base oils.

Chemical additives can comprise 20 percent of a typical multi-grade oil. Photo by Jim Marotta.

How Do I Know When My Oil Needs To Be Changed?

One solution presented by the automobile manufacturers is an oil life monitor. Several types of systems exist that use technology to directly “read” the oil. The most popular of these systems rely on capacitance. Using two conducting plates separated by the oil, which acts as an insulating fluid, the system calculates a base capacitance number. As the oil degrades, the system measures the change in capacitance.

Other systems use algorithms to predict oil change intervals.The algorithms are based primarily on factors such as driving habits, driving speed, and failure to replenish low oil levels. Research determined that these factors contribute to oil breakdown. The algorithm method systems also monitor time between oil changes, vehicle speed, coolant temperature, load signal, engine rpm, engine oil temperature and engine oil level to determine the remaining time and mileage before the next oil change. General Motors’ Oil Life System and Chrysler Corporation’s Flexible Service System (FSS) are good examples of this type of system.

General Motors’ Oil Life System is based on algorithms that attempt to predict oil change intervals. Photo courtesy of GM.

Goodbye Dipstick?

A new multifunctional system determines oil level and oil condition. The system determines viscosity using a piezoelectric listening device. When this sensitive surface comes into contact with the oil, the oscillation frequency and damping change according to the oil’s mechanical properties, allowing viscosity to be measured. The addition of oil level sensing capability may allow vehicle manufacturers to remove the oil dipstick from the engine.

So, the best answer to our question of how long engine oil lasts is, “it all depends.” Follow the manufacturer’s fluid specifications and maintenance intervals when servicing your vehicle. Check your owner’s manual or get them at www.ChiltonDIY.com or www.ChiltonPRO.com, where a subscription to comprehensive service procedures, specifications, Technical Service Bulletins, and wiring diagrams, gives you the information to do the job right.

James Marotta A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

26 Responses to “Oil Change: What is the best maintenance interval?”

  1. Patrick says:

    Does changing the oil regularly affect the emissions?

  2. Brendon Ross says:

    Hey Jim!

    Thanks for the great info. I still have one question though. I drive an older Acura Integra and am experiencing some oil leakage. Will just topping it up every once in awhile until around the 5000KM mark when I should get a full oil change be enough to keep my car running smoothly?

    Cheers
    Brendon

    • ChiltonDIY says:

      Hi Brendon, it’s Chilton.
      If you have a leak which requires adding oil at 5000k, you need to get that fixed. That’s not a small leak. Change the oil and filter at the intervals given in the owner’s manual. The maintenance intervals are also in your ChiltonDIY subscription.

  3. kelly says:

    Great blog!

  4. sasha says:

    ya it was a nice blog and quite informative

  5. Jodi Triplett says:

    It is important to remember that each vehicle is different when it comes to how long you should wait in between oil changes. Older vehicles differ greatly from brand new vehicles. As Chilton mentioned, you should check the manual of your vehicle for the best info for that particular vehicle.

    • ChiltonDIY says:

      You make a good point Jodi!
      In addition to the owner’s manual, it is a good practice to check the technical service bulletins (TSBs) for your vehicle as carmakers sometimes give new recommendations. For example, a carmaker may recommended a new type of oil or antifreeze or less frequent fluid changes in response to changing technologies.
      You can keep up with TSBs and Recalls for your car or truck in your ChiltonDIY subscription.

  6. car mechanic mississauga says:

    such an excellent advice, I have a question, what is the best type of car engine oil available in the market?

    • ChiltonDIY says:

      Hi there. As a car mechanic you must have some good pointers about engine oil, share your thoughts with us!

      Generally, the best engine oil at minimum meets the carmaker’s specifications. The wrong oil may void a warranty and/or damage your vehicle.

      Engine oils have changed a lot over the years, so even for older models, the carmaker’s recommendations may be different than when the owner’s manual was originally printed. Sometimes a carmaker will announce a fluid specification change in a technical service bulletin, so periodically check the bulletins for your vehicle in your ChiltonDIY subscription.

      Most 2014 models call for 7500-10000 miles between oil changes. What’s behind the lengthening intervals between oil changes? Improved technology and our need for clean water: Used oil from just one typical oil change could ruin a million gallons of fresh water—a year’s supply for 50 people, according to the EPA.

      What can you do? Avoid unnecessary oil changes: Follow the carmaker’s recommendations for oil change frequency. Consider re-refined oil, which can be as good or better than virgin oil. Mercedes uses re-refined oil in every new vehicle manufactured in Germany according to the city of Santa Monica Office of Sustainability and the Environment.

  7. Edoubts says:

    Thanks for sharing this perfect information.

  8. Rick A. says:

    I acquired a 2011 Mercury Mariner (26,000 mi/4cyl-2.5 liter)and which the Ford dealer says was serviced with a “synthetic blend” oil. The car’s Manual says only to change it when the Oil Monitoring Message tells indicates that a change is needed. But, the Ford dealer says it should be changed every 3000 miles! Edmonds.com says that year, make and model should have an oil change evary 7,500 miles, yet I have heard that most oil filters will not last for more than 5,000 miles. For the record, only I maintained my own cars back in the 70’s, I am not a mechanic, but I have worked with electronica and computers most of my life. Therefore, I do not have much faith in such “Oil Monitoring Message” systems being totally in control of something as crucial as engine oil. I would would like to error on the side of caution at 4,000-5,000 mile; please let me (and others) know your expert opinion. Thanks, Rick

  9. vin decoder ford says:

    Proper tire maintenance improves vehicle handling, fuel economy and tire wear and prevents your maiming or death or at least the destruction of your automobile..Specially maintenance is most important part of the car…

  10. timothy brad says:

    Informative tips on your post! When I purchased Honda parts in Toronto and consulted a performance and repair specialist this info also struck me!

  11. Ralph says:

    Great Post!

    With today’s technology, do you think the mileage for a standard oil change still needs to be done every 3,000 miles? Or has the miles until a needing changed gone up?

    What makes it sound like it should, is that it’s 2014 and we’ve come a long way since that 3k mile oil change standard was made.

    But also, 3,000 miles back in the day might have taken a half year to a full year to drive. We drive a lot more than we did back in the day, so the 3,000 miles come quicker so I can see why the average time to change the oil hasn’t changed at all.

    I’d love to know your input on that!

    • ChiltonDIY says:

      Hi Ralph.
      Are you saying that in general people drive more miles now on average than in the past and so the time interval between oil changes may be similar, even though the recommended oil change interval is lengthening from every 3,000 miles to 7,500-10,000 miles or more?
      With today’s technology the carmakers’ oil change interval has lengthened considerably, saving time, expense, and environmental damage. As we noted earlier, according to the EPA one do-it-yourself oil change could ruin a million gallons of water.

      “Used motor oil is insoluble, persistent and can contain toxic chemicals and heavy metals. It’s slow to degrade. It sticks to everything from beach sand to bird feathers. Used motor oil is a major source of oil contamination of waterways and can result in pollution of drinking water sources.” – EPA Used Oil Management Program

      The rule of thumb is the vehicle maker’s recommendations for the frequency of oil change. Often the carmaker will change these specifications as technology changes. When carmakers change their recommendations they issue a technical service bulletin (TSB). You can view the TSBs for any particular model when you subscribe to ChiltonDIY or ChiltonPRO.
      Some factors may affect the oil change interval. The operating conditions of a vehicle are a factor. A racecar for example will have different requirements from a vehicle with mostly highway miles. The vintage of the vehicle is a factor. Older vehicles may have different requirements than newer ones.
      In addition, many vehicle have a “maintenance minder” type system or engine oil life monitor which monitors driving distance, type, etc. and lights an indicator when it’s time to have the oil changed.

  12. Jon Mossefin says:

    Such an informative article. I would have to agree that different cars have different intervals in oil and filter changing. Old cars, especially, are more prone to engine problems that’s why they need shorter time intervals compared to newly-purchased vehicles.
    -Wise Auto Auto Mechanic

    • ChiltonDIY says:

      That’s a good point, Jon. :)
      Whether the vehicle is “old” or “new,” car owners can follow the vehicle manufacturers’ current recommendations to stay on the safe side. Maintenance recommendations take into account the driving conditions, such as frequent stop-and-go driving, which can require more care.

      • Petron Lubricants says:

        That’s right Jon! For example my 3 month old Ford Ecosport, it is scheduled to have its first oil change once I hit 10000 Km on my mileage. Unlike my 7 year old Honda Civic, I usually change oil and filter every 5K km or 6 months.

        Engine Oil is really important and crucial to engine wear and tear.

        My rule of thumb is the more often, the better!

        Thanks for this awesome article!

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