• Engine oils need to be replaced at a certain time interval because they undergo chemical and physical changes while in use that keep them from performing their functions. 
• Oil change intervals increased during the past 25 years due to better base stocks and more robust additive packages.
• Future increases in oil change intervals are likely, but other OEM priorities such as improving fuel economy and moving to alternative technologies will make it more challenging for the lubricant industry to produce fill-for-life engine oils.

The growing performance demands placed on today’s passenger car engine oils have led to the use of lower-viscosity lubricants needed to meet more demanding fuel economy requirements. But these lower-viscosity engine oils also raise concerns about the potential for increasing engine wear. 

Higher-temperature operating conditions combined with the use of a lower quantity of engine oil also has put more pressure on the durability of these lubricants. In addition, other issues such as low speed pre-ignition (LSPI) have led lubricant suppliers to evaluate changes in the engine oil formulation to a different detergent. 

The potential onset of GF-6 (1), which has been delayed due to the need for developing and approving new test specifications, has only pointed to the challenges of developing passenger car engine oils that will meet current and near-future demands of internal combustion engine-powered vehicles.

One other issue that is evolving concurrently is the question of how long consumers should wait to change their engine oil. The use of better base stocks and additives has led to the belief that passenger car engine oil change intervals have increased, but there still appears to be uncertainty about when an engine oil should be changed.

This article provides perspective on how passenger car engine oil change intervals have changed in the past and where they are currently. Key industry experts were asked not just about these issues but also to provide insight on how engine oil change intervals will change in the future. As some other lubricants can be used for the lifetime of the machine, is there a possibility that passenger car engine oils can be used for the lifetime of the vehicle?


© Can Stock Photo / nanDphanuwat2526

The following experts were interviewed. 

1. Jeffrey Guevremont, American Refining Group, Inc.
2. Dr. Jai Bansal, Argonne National Laboratory
3. Robert Stockwell, Chevron Oronite Co.
4. Lake Speed, Jr., Driven Racing Oil
5. Michael Seemann, Evonik Resource Efficiency GmbH - Oil Additives
6. Paul Harvath, General Motors
7. Jeff Thompson, Infineum USA LP
8. Dr. Peter Lee, Southwest Research Institute
9. Dr. Donald Smolenski, Strategic Management of Oil, LLC.

Need to change engine oil
Before discussing trends in passenger car engine oil change intervals, the experts were asked to first discuss why this automotive lubricant needs to be removed after a certain period of time and replaced with virgin material. STLE-member Dr. Peter Lee, staff engineer-chief tribologist at Southwest Research Institute in San Antonio, Texas, says, “In modern engines, the oil undertakes a number of functions: lubricating the many different interactions between engine components, reducing wear and friction, cooling engine components, removing engine wear particles and acting as hydraulic fluids for items such as chain tensioners, variable valve timing and valve adjusters. 

“In order to achieve all of these functions, the base lubricant has an additive package, which typically includes (among others) antiwear, antioxidants, antifoam and friction modifiers,” Lee adds. “These lubricants are expected to perform to a very high standard while operating in severe conditions across a range of tribological contacts. Ultimately the additives are used up as they perform their function in the engine and both base oil and some additives are sheared in the operating engine and degraded through thermal oxidation in the hotter areas of the engine such as the piston assembly and the turbocharger. The lubricant also oxidizes over time. Therefore, simply put, the engine oil needs to be changed as it becomes worn out and cannot perform as required.”

Robert Stockwell, industry liaison, Global Automotive Engine Oils at Chevron Oronite Co. in San Antonio, indicates that passenger car engine oil needs to be changed due to oil degradation. He says, “Five reasons that cause oil to degrade or wear out include (1.) oil contamination with water and fuel condensation in colder climates, (2.) oxidation that occurs while the engine is running under high-temperature conditions, (3.) contamination by combustion byproducts, (4.) shearing forces that the oil is subjected to during operation and (5.) depletion of corrosion-prevention additives, which are preventing corrosion in the engine.”

STLE-member Dr. Jai Bansal, retired in 2014 from Infineum International as the global technology advisor and currently an advisor to Argonne National Laboratory in Argonne, Ill., states that the composition of engine oils changes over time, necessitating the need for removal. He says, “During its lifetime in the engine, the oil undergoes all kinds of chemical and physical changes due to extreme thermal, oxidative and mechanical stresses present in the engine. Consequently the performance of the oil continues to deteriorate with time in the engine. There comes a point when the oil is no longer capable of providing adequate protection against wear, deposits, sludge formation and other undesirable processes in the engine. It is therefore imperative to drain the oil before it reaches that point and replace it with a fresh charge.”

Jeff Thompson, market manager PCMO & HDD for Infineum USA LP in Linden, N.J., believes that key components in the oil consumed during the operation of the automobile ultimately lead to the need for changing the oil. He says, “During the operation of an internal combustion engine, the oil is subjected to elements and conditions that consume the protective benefits of the additive package. For example, combustion events create acidic byproducts and, through some combustion blow-by, depletes the protective base (base number) componentry in the oil. 

“At the same time, the extremely hot environment inside the engine also is ripe for oxidation, which can create issues such as oil thickening and deposits,” Thompson says. “Antioxidants are consumed in this process, and these components need to be replenished. Less obvious, wear protection chemistry also can create sacrificial layers as they protect metal surfaces under load, and that chemistry also needs to be replenished. The oil also safely captures ‘bad actors’ like soot through dispersant chemistry. Eventually the oil needs to be replaced to eliminate soot from the system before too much accumulates that can be safely managed.”

STLE-member Paul Harvath, technical specialist for dexos™ lubricants for General Motors in Pontiac, Mich., says, “Engine oil provides lubrication and cooling for the engine but also is the trash can for all artifacts of the combustion process. The trash includes combustion remnants, partially burned fuel, degraded engine oil and spent additives. An oil change amounts to taking out the trash and, of course, always requesting that it be properly disposed.”

Michael Seemann, OEM relations manager, Evonik Resource Efficiency GmbH - Oil Additives in Darmstadt, Germany, also agrees that consumption of additives in the oil is an important reason for needing to do an oil change. He says, “While shear stable viscosity index improvers do not change much, oxidation, nitration and acidification will deplete their respective additive levels. In addition, active wear protection ingredients need to be refreshed.”

STLE-member Dr. Donald Smolenski, principal, Strategic Management of Oil, LLC in St. Clair Shores, Mich., feels that the condition of the oil is based on the vehicle’s driving conditions. He says, “Engine oil degrades over time, depending upon the type of service to which it has been exposed. For instance, in short-trip, low-temperature operation, unburned fuel and condensed water contaminate the oil, reducing its viscosity and reserve alkalinity and possibly hydrolyzing key additives. In high-speed, high-temperature operation, the oil oxidizes, becoming more acidic and increasing its viscosity.

STLE-member, Lake Speed, Jr., principal, Driven Racing Oil in Huntersville, N.C., points out two causes for needing to replace the oil. He says, “Contamination from condensation or fuel dilution are both grounds for condemning an oil before reaching the oxidation threshold. This also is true for dirt contamination.”

STLE-member Dr. Jeffrey Guevremont, principal scientist/R&D applications manager for American Refining Group, Inc., in Bradford, Pa., focuses on two reasons for replacing the oil. He says, “The primary reason is to get rid of the oxidation and other decomposition products that occur during the use of the engine oil. Second, you are refreshing the additive supply for both oil protection and engine protection.”


© Can Stock Photo / cgteam

Oil change intervals in the past
Stockwell says, “Over the years, engines, oils and fuels have all improved in quality, which has led to the ability of consumers to wait longer in making oil changes. Twenty-five years ago, the common oil change recommendation was typically every three months or 3,000 miles. Many manufacturers now recommend oil changes in the 5,000-10,000-mile range (although there are exceptions such as shorter intervals in China, where lower quality fuels are still common). Many vehicles now have maintenance reminders that typically extend oil change intervals.”

Stockwell lists five factors that led to the increase in oil change intervals. He says, “Modern engines have much less blow-by than they had years ago, so the oil is exposed to fewer combustion byproducts. Modern gasolines burn much cleaner and are much less prone to create sludge than fuels from 10 or 20 years ago. Fuel injection helps to keep air:fuel ratios near optimal. Engine oil categories in the U.S. are going through upgrades about every five or six years, and with each upgrade comes better engine protection, more durable oils and better fuel economy. The trend of increasing the amount of oil present in the sump also increases oil change intervals.”

Bansal says, “Oil change intervals in North America have been slowly increasing with time. From a starting base of about 3,000 miles in the early 1990s, it is not uncommon to see 10,000-mile recommended oil change intervals in North America today.” 

Bansal furnishes several other factors beyond the primary one (improvement in the performance of the oil) that have led to an increase in oil change intervals. He says, “An increase in the leased vehicle segment reduced the motivation for those individuals who are leasing to have their oil changed. Additionally, the OEMs’ desire to compete on infrequent warrantee-mandated service trips and environmental considerations have provided strong motivation to lengthen drain intervals.”

Smolenski believes that the OEMs assisted in increasing oil change intervals by providing guidance to consumers. He says, “Years ago vehicle owner’s manuals generally advised the driver to change their oil in three months/3,000 miles in ‘severe service’ or after one year/7,500 miles, which was defined as ‘normal service.’ Severe service was defined as short-trip, low-temperature operation, high-speed, high-load, high-temperature operation or extended idle. Quick lubes generally recommend the shorter interval. To minimize consumer confusion, many OEMs used algorithm or sensor-based systems to assist with instructing when to change the oil. The result was 5,000-6,000-mile oil change intervals became common with some intervals extended to 10,000 miles or more.”

Smolenski continues with stating that formulating engine oils with better base stocks and additives led directly to increases in oil change intervals. He says, “Moving from API Group I/II base oils to Group II/III/IV base oils was a significant improvement. This, combined with more robust additive packages, provides oils with improved detergency, dispersancy, oxidation resistance, antiwear, etc., which allowed intervals to be safely expanded. These improvements also helped to address OEM challenges such as higher engine oil temperatures, lower oil consumption rates resulting in fewer oil addition, etc.”

Thompson claims that advancements in oil, oil monitoring and large sump sizes have all enabled drain intervals to increase from 3,000 miles, which was the standard 25 years ago, to 5,000 miles or longer. He says, “Advancements in the oil additive package as well as more and better additive chemistries per quart provide increased protection. Monitoring correlates the conditions the oil is exposed to during its time in the engine. If an engine is being driven in more severe conditions, the drain interval will adjust accordingly. The larger sump size allows for more oil and chemistry as a whole to enable the longer drain intervals. With these advancements, in some cases OEMs and oil marketers have endorsed drain intervals as high as approximately 15,000 miles, when better oil, better oil monitoring and larger sump sizes are all combined.”

Speed says, “The OEM push for longer drain intervals and the inclusion and acceptance of synthetic base stocks have led to a significant increase in oil change intervals.”

Guevremont says, “The trend toward longer oil change intervals required both chemical (base oil and additives) as well as technical (car manufacturing design and tolerance improvements and oil condition monitoring) developments.”

Harvath says, “Due to improved oil specifications such as those developed by OEMs, oil change intervals have gotten longer. Improved change periods depend on each specific OEM and their oil life measurement system.”

Harvath continues, “The change of base oils from Group I to the currently used Group III and IV in engine oils has been a big driver along with improvements in additives and engine oil specifications. Engines have generally improved with lower oil consumption as well.”

Seemann indicates that over the past 25 years, oil change intervals in Europe increased from 5,000 km or six months to a maximum of 30,000 km or one year, whichever comes first. Some European OEMs have oil change intervals that last up to two years. Seemann feels that three factors facilitated an increase in oil change intervals: fuel quality, engine development and engine oil quality.

Seemann says, “Low sulfur fuels and the use of metal-free fuel additives enabled longer oil change intervals. For passenger car diesel engines, the soot level declined from 5% after 7,500 km 20 years ago to a maximum of 1% after more than 30,000 km today. Engine oil technology also needed to improve to handle significant increases in power density. For example, a 1.6-liter, 4-cylinder gasoline engine nearly tripled in power per displacement volume from 34 kilowatts per liter in 1991 to 92 kilowatts per liter in 2014.”

Lee feels that oil change intervals have changed in the U.S. and in Europe in different ways. He says, “In the U.S. there has been a steady increase over time in the oil change interval with most cars now being driven for 7,500 or 10,000 miles with some as high as 15,000 miles between oil changes. Oil change intervals increased in Europe until about a decade ago when they decreased slightly due to an increase in the complexity of engines and power densities.” 


© Can Stock Photo / vchalup

Consumer confusion
Perception that consumers are confused about when to change the oil in their automobiles led to the request for the article contributors to comment on this and also on the myth that the proper oil change interval is 3,000 miles. 

Harvath says, “As a lubricant professional the two questions I always hear are what oil to use and when do I change it? Considering how often I hear those questions, there appears to be quite a bit of confusion on the topic! The simple answer is to read the manual for your vehicle. Regardless of the brand, be sure to use the proper oil specification and use the change intervals laid out in the owner’s manual.”

Harvath believes that the myth that oil change intervals should be 3,000 miles was passed down to current consumers from previous generations. He says, “I first heard about this from my father in the 1960s and I suspect most people had a similar experience. Where it started is a subject for a historian, but the legacy transfer of knowledge is a power tool, and this interval is still around and will be for a long time. OEMs are trying to change this for the good of the consumer so that they do not incur unnecessary costs and likewise make sure they are receiving the required engine protection.”

Bansal says, “Historically the oil service industry has heavily promoted the concept of changing oil every 3,000 miles. Even though the oil quality has undergone major upgrades over time to render this concept invalid, there is a significant segment of the consumer base that continues to believe that frequent oil changes are ‘relatively inexpensive insurance’ for their investment.”

Bansal continues, “There was a major and sustained marketing campaign by certain leading oil marketers in the 1980s and 1990s to promote the 3,000-mile oil change interval in North America. They also managed to sell this concept to automotive OEMs so the practice was embedded into the vehicle user manuals as well. To be fair, the OEMs may also have been reacting to the prevalence of poorly regulated oil qualification process prior to the advent of the ILSAC system and the ACC Code of Practice in the early 1990s. Even though the rationale for such oil change intervals no longer exists, the residual effect of that practice lives on to this day.”

Smolenski says, “I believe that consumers are much less confused (not well informed, just less confused) than in the past. Most vehicles now tell the driver when to change their oil, although many drivers may behave conservatively relative to what the indicator tells them. Or they can follow the quick lube sticker recommendation, which is usually 3,000 miles. The likelihood of someone not changing their oil at all is very unlikely now, at least.”

Conflicting information consumers obtain from those who service their automobiles also does not help with finding the proper oil change interval for their vehicles. Smolenski continues, “The 3,000-mile interval is quite often sold as ‘cheap insurance,’ a way to protect an expensive asset. Consumers may still believe it because that was the interval their parents used, or what the quick lube or the mechanic recommends (not considering their vested interest in shorter intervals = more business). There also may be some mistrust about automobile dealers trying to drum up more business by recommending intervals that result in more repairs. This really does not make sense, however, when powertrain warranties are often 100,000 miles or more.”

Guevremont says, “There is a discrepancy between oil change interval claims between car manufacturers and various oil manufacturers, which leads to consumer confusion. For a long time, 3,000 miles was the promoted drain interval. And now, as we are able to create oils that can protect and lubricate engines for longer intervals, it is difficult to change what has been the norm for so long. Internal oil condition monitors on vehicles appear to be helping to break this trend by shifting some of the consumer thinking toward letting their car tell them when an oil change is needed versus keeping the sticker often put on the windshield as a reminder for their next oil change (and with writing that often fades in the sun).”

Speed says, “Confusion still exists about how many miles an automobile should travel between oil changes. Consumers tend to know that 3,000 is too short but have divergent opinions on whether to wait 5,000, 7,500, 10,000 miles or more.”

He continues, “Decades of advertising have drilled the 3,000-mile oil change interval into the minds of consumers. They still consider 3,000 miles to be a safe bet.”

Lee believes that confusion among consumers is not the issue, rather, lack of interest and education. He says, “Many U.S. consumers stick with what they have grown up with, a 3,000-mile interval. Others follow the oil change sticker placed in their window at the last oil change. Some owners only take their car for an oil change when the oil service light comes on. Very few people actually take the time to read the car instruction manual and change the oil as directed by the OEM. Others ignore all and run way past the recommended intervals. In Europe, the service manual or oil monitor light is the main guide for oil changes.”

Lee points out that one reason for this problem is that advances in vehicle technology and appearance are obvious to consumers, but advances in oils cannot be seen. He says, “The 3,000-mile oil change interval began decades ago when oils and cars were not as advanced as they are today. The lack of engagement from consumers has led to a wasteful cycle that results in approximately three times as much contaminated oil being produced as necessary.”

Seemann says, “Even when OEMs utilizing oil life monitoring allowed customers to go for over 10,000 miles, some customers were still in favor of earlier oil changes. To his understanding, there was a time when OEMs allowed to run for 6,000 miles under regular driving conditions and up to 3,000 miles under severe driving conditions (e.g., taxis and towing). To be on the safe side, consumers seemed to be willing to follow the 3,000-mile recommendation or were convinced in dealing with quick lubes. Today, this is clearly an old-fashioned rule unless a consumer drives only 3,000 miles per year and has the oil drain light turn on.”

Thompson says, “Consumers have comfort with the 3,000-mile oil change interval as it has existed for many years. No performance downside has been found for maintaining a shorter oil change interval, only added costs. Some consumers view this interval as peace of mind and worth the protection it provides an expensive automobile investment. Some consumers may be skeptical that oil change interval extensions could represent more marketing campaigns or cost savings versus a scientifically substantiated and advanced technological basis. Without further education to the end-user about the basis of drain interval extensions, some may remain skeptical.”

How often should oil be changed today?
All of the respondents indicated that consumers should follow the guidelines of their OEM, which is found in the owner’s manual and today mostly indicated by an oil drain or service indicator. 

Guevremont provides further guidance: “For fully synthetic oils, the oil change interval can be extended significantly. Literature for the vehicle and from the engine oil manufacturer must be reviewed by the consumer to figure out how far to push out the change interval. A word of warning has to be added for synthetic blends or semi-synthetic engine oils. They offer improved performance, but there is no set industry standard for how much they will improve the life of the engine oil. Consumers using these oils should be cautious in determining when to make an oil change.”

While agreeing that consumers should follow OEM guidelines, Lee notes that oil change intervals should depend on driving styles and habits. He says, “Automobiles that drive only very short distances and not very often will need an oil change in fewer miles than a car that has a regular highway commute of a reasonable distance. Vehicles driven shorter distances that do not have the time to warm up to full operating temperature cannot burn off the water and fuel dilution that occurs in the oil. If an automobile is driven hard or spends a significant time towing, then the oil will have experienced higher operating temperatures, and an oil change will be required sooner than a car driven gently on a daily commute.”

Lee continues, “Consideration should be made that OEM recommended oil change intervals are based on the vehicle’s factory filled oil. If an older automobile can accept a synthetic engine oil, the OEM recommendation will be out of date, and the oil change interval can be longer.”

Hybrid and plug-in electric vehicles
In discussing oil change intervals, the discussion has focused solely on internal combustion engines. But consideration should be given to hybrid and plug-in electric vehicles, whose use is increasing globally. 

Seemann says, “In my view the current high-quality engine oils are fully suitable for hybrid applications. The impact on oil change intervals with hybrids is expected to be even more dependent on the consumer driving profile that affects real operation time and the operating condition of the combustion engine. This means that the oil drain/service indicator will play a larger role.”

Thompson draws a distinction between hybrid engines that operate to directly drive the powertrain and advanced hybrids. He says, “The former may not see significant changes in oil change intervals versus their non-hybrid counterparts as they operate somewhat similarly. Advanced hybrids or plug-in electric hybrids that have an engine operating more as a generator may see shifts toward time of operation and operational cycle. Oil change monitors may play a larger role in ensuring oil is changed since miles driven do not as directly correlate to what the oil has experienced.”

Speed says, “Oils that are formulated specifically for series hybrid applications could achieve oil change intervals over 20,000 miles.”

Bansal says, “Hybrids may be able to support longer oil change intervals than conventional designs. However, the frequent engine start/stop nature of the hybrids will likely pose some unforeseen performance challenges for oil formulators, which may impact oil change interval expansion until oil formulators develop satisfactory responses to these challenges. Even longer oil change intervals can be potentially supported by the plug-in electric vehicles.”

With the potential for longer oil change intervals, Bansal says, “If the vehicle has to be serviced at certain time intervals (e.g., once a year) for non-oil related issues, does it really make sense to invest in oil technologies for oil change intervals significantly longer than the ‘regular service intervals?’”

Lee says, “In vehicles where the engine continues to be the primary power source, oil changes will match those of non-hybrid vehicles. However, in vehicles where the electric motor is the primary power source a time element will be included. For example, the Chevrolet Volt has a maximum two-year oil change as its feasible that a Volt could be used daily for two years without the engine running at all, but the oil would still need changing.”

Harvath says, “Hybrids have been out for a while and have established their needed oil change intervals. Pure electric vehicle owners may forget that they need to change the oil if they return to an internal combustion engine powered vehicle.”

Guevremont says, “If the firing time of combustion is reduced by driving a hybrid, then oil change intervals could improve. By removing the combustion process all together in a fully electric vehicle, this can result in even longer oil change intervals.”

Smolenski considers estimating the oil change intervals for hybrid and plug-in electric vehicles to be a challenge to figure out. He says, “One solution might be to change the focus of determining oil change intervals from what the vehicle experiences to what the engine experiences. For instance, if a conventional vehicle is taken on a trip of 60 miles, that oil is fully warmed up for most of the trip—pretty easy service. But if a hybrid electric vehicle runs 56 miles on the battery before the internal combustion engine turns on, this engine has only ‘seen’ a four-mile trip—pretty harsh if it is in cold weather.”

How far can oil change intervals be extended?
The improvements in the design of the engine and better formulated oils have led to the increase in oil change intervals. Assuming this trend continues in the future, the respondents were asked about how far oil change intervals can be extended and the possibility of having the original oil last for the lifetime of the vehicle.

Stockwell says, “As engines, fuels and oils continue to get better and better, oil change intervals will continue the trend toward higher mileage intervals. Oil change intervals in Europe for some vehicles have been recommended at two years or 30,000 km for some time now. With very high-quality engine oils and careful engine design, this can be done. However, engines do consume some oil during normal operation, so with longer oil change intervals, it becomes more important for the consumer to check the oil level regularly or for the engine to have an engine oil level sensor.”

Harvath does not predict that the automotive industry will be focusing on changing the oil change interval in the future. He says, “Most OEMs are paying attention to developing alternative technologies such as electric vehicles and fuel cells. If an attempt is made to achieve a fill-for-life engine oil, then consumer choices such as the varying quality of fuel, hostile environmental conditions and the duty cycle associated with the vehicle all will force a very high level of engineering consideration. Options that will need to be examined include an expanded oil sump size, filtering capacity, a significantly elevated additive level in the initial oil and perhaps a way to supplement additives into the lubrication system as the vehicle ages. These are expensive and daunting challenges.”

Speed contends that the use of direct injection engines by OEMs will likely shorten oil change intervals in the future. He says, “The problem limiting oil change intervals is the soot generated in direct injection engines. Only by increasing the sump capacity will OEMs be able to maintain or extend oil change intervals.”

For the future, Speed feels that further increases in oil change intervals are dependent upon fuel blends and engine architecture.

Thompson says, “Automobiles are likely to continue to see some oil change interval extensions into the future as the demand for oil performance increases and engine manufacturers look to simplify maintenance intervals for the end-user. But it is unlikely that oils will become fill-for-life fluids due to their service requirements, need to maintain a reasonable engineering design for the oil system and costs. Some extension of oil change intervals is likely, but it should align with other vehicle maintenance needs and will be bound by maintaining reasonable costs and engineering designs for the oil and the engine.”

Bansal feels that improvements in oil quality will continue due in part to the increasing use of synthetic base stocks, but there will be technical challenges along the way. He says, “Some of the emerging engine technologies might pose unforeseen challenges for the oil formulation technology, which in turn may retard oil change interval progression—at least for a period of time.”

Bansal sees the odds for fill-for-life oil to be slim. He says, “The internal combustion engine exposes the oil to plenty of thermal, oxidative and other stresses such that the oil necessarily degrades in service and, therefore, must be drained at some point. The European experience clearly shows that oils with 15,000-20,000 mile oil drain intervals can be designed with advanced additive technologies. The question is whether the size of the potential market for such long oil change intervals will support the required technology investments.”

Seemann says, “While engine oil specifications (such as ILSAC, ACEA, JAMA and OEM) continue to update high oil quality standards to make sure they are compatible with modern engine technologies (e.g., downsized direct injection gasoline and diesel engines with enhanced exhaust aftertreatment systems), no movement is seen to further increase oil change intervals in the near future. Another challenge is that stress on oils will continue to increase as power densities and engine temperatures rise. Higher oil volumes might lead to longer change intervals but the added weight works against fuel economy. Efforts to introduce additives during engine operation to extend the life of the oil do not seem promising because aged components cannot be removed from the oil.”

Smolenski predicts that oil change intervals may increase due to the ongoing trend to reduce required maintenance for consumer convenience. But this will need to be balanced by the need to increase fuel economy, an issue consumers care very much about.

He says, “The idea of fill-for-life engine oils does not appear to be outlandish because many transmission oils now operate in this manner. But engine oils are exposed to significantly more contamination (e.g., blow-by) than automatic transmission fluids. The use of extremely high-quality engine oils and a larger oil sump could help to enable such a fill-for-life scenario. However, the increased cost of such an oil, the added weight to the vehicle, the considerable oil consumption over 100,000 miles and potential negative effects on fuel economy with oil aging would all have to be overcome.”

Lee says, “Oil change intervals will continue to increase in the future due to improvements in oil formulations and engines. A series of factors such as changes in sump size, fuel economy retention requirements of used oils and effects of lower viscosity grades (e.g., 0W-8 and 0W-16) may affect the length of time the oil can remain within specification. The automotive industry is a very long way from having fill-for-life oils. Valvetrain oils could be a possibility if the engine oiling system were split into two, but oil exposed to the heat and gas generated during combustion and the extreme temperatures in the turbocharger will need at some point to be replaced.”

Guevremont believes there will be a continuing push for longer oil change intervals in the future with additive improvements becoming the key factor in further improving oil performance, but the push for higher fuel economy may act to hinder progress. He says, “The lubricant industry is probably at a plateau for using base stocks to get more life from engine oils. Additives may become the primary driver, but the higher cost involved will need to be balanced with the value added from marketing longer oil change interval oils. Fuel economy also could be a significant factor as reducing viscosities may lead to a greater chance that lighter additive chemistries exhibiting greater volatility may negatively impact oil performance including reducing operating life.”

Fill for life is not seen by Guevremont as a possibility in an internal combustion engine. He adds, “A much longer oil change interval could be a possibility for an electric vehicle using current lubricant technology. But the possibility of a 10x lifetime improvement for an electric motor may prevent the oil from being filled for life. Much greater electric motor life may lead to a requirement that oil last for one million miles, which would be very challenging.”

Oil change intervals will most likely continue to increase in the future. But higher priorities such as the trend for increasing fuel economy and significant technical challenges will need to be overcome in order to develop fill-for-life oils.

REFERENCE
1. Rensselar, J. (2018), “Countdown to GF-6,” TLT, 74 (8), pp. 30-38.

Neil Canter heads his own consulting company, Chemical Solutions, in Willow Grove, Pa. You can reach him at neilcanter@comcast.net.