Written by: The Feisty Goat Last Edit: 11/29/23

Imagine this: $160-250 a year could double the service life of your car, reduce your need for a monthly car payment, and save you the unplanned cost of a $10k engine replacement. Would you listen?

Because that’s precisely what’s at stake in this discussion.

Grab a glass of your favorite wine, bourbon, tea or coffee. There’s a lot to cover here, but I’ll try to keep it concise. Below is the annotated backstory that brought us to the age of prolonged oil changes and failed engines that could have been saved.

This article will cut through all of the myths and misinformation currently circulating in the automotive industry and its community of loving enthusiasts (the latter of which I am a lifelong member), on the subject of oil changes.

Understanding this short timeline of events will give you context for why running your engine out to 10k or even 15k miles, on the same oil and filter, is a risky endeavor that simply isn’t worth the gamble, even if some folks have gotten away with it for a limited time.

The long-term issues are only just now being discovered. The reasons for this stance will also be covered below.

The Dinosaur Ages

If you’re over the age of 35-40, you might remember when the recommended oil change intervals (OCIs) on cars and trucks was ~3000 miles. This was a time when cars and engines were using cheap, conventional “dinosaur oil” that would break down over time and have to be drained and replaced. At $3-4/qt, it was completely reasonable and forgivable.

It’s noteworthy that this was also a time period in which most engines on North American roads were naturally aspirated: pistons and cylinder heads breathing and compressing the same air as humans.

N/A motors, when properly designed, will always run cooler than a forced induction motor, which makes them easier on internal parts, oil, and their respective cooling systems. This is why they are still the favored choice in most racing and endurance classes.

In the 1990s, turbocharging became the norm for gas-powered sports cars and diesel engines, and by 1999, European makes were most interested in turbocharging their smaller engines to improve fuel economy and performance. We’ll circle back to this in a minute.

Short oil change intervals. Dinosaur conventional oil. N/A motors. Got it. Let’s keep moving.

Synthetic oils changed everything…

Synthetic oils have been around for nearly a century now, but their use in automotive mainstream has truly taken off in the last ~30 years (and in motorsport for a bit longer).

Synthetic oils are far more chemically stable, even in the presence of prolonged heat and friction. They can maintain their viscosity and lubricity over a wide range of temperatures, and cars can go longer intervals (safely) between oil changes. They’re honestly worthy of making the list of modern engineering marvels, along with antibiotics, 20th century vaccines, and Christina Hendricks.

Turbo and supercharged engines (called forced induction whenever air is compressed into a motor) can and do get very hot in a hurry, especially in the southern US during the 6 warm months of “mostly summer”.

Forced induction engines needed all of the improved properties a synthetic oil could offer, so by the early 2000s, it was a requirement for many engines, and a consideration for N/A engine owners looking to gain a performance improvement.

This is also where the felonious myth of “switching from conventional to synthetic will hurt my engine” originated. I won’t even address that crass myth here. Unless you really want me to…

So yes, using synthetic oils, you can safely go much longer between services. We’ll call it an “OCI” from here forward in this article (oil change interval).

But “longer” intervals doesn’t tell the full story.

You can come back later and deep-dive synthetic oils if you want to expand your knowledge base:

Supplemental reading: https://www.caranddriver.com/research/a32879214/synthetic-oil/

Short sidebar…customers often ask “where does my old oil go? I’m kind of worried…”

[waste recycling oil pic here]

The Green Party

What happens to all that oil after it’s drained? Landfill bound? Fertilize my lawn with it?

For the environmentally conscious folks, oil has been recyclable for some time, after which it is repurposed for other uses in the petroleum industry, including the creation of asphalt for roads and paving, so its life cycle does not end when you drain it from your engine.

Therefore, the oil change interval is solely at the discretion of the driver/owner, and does not harm the environment by doing so more frequently.

You and your wallet make the judgment call, but do so armed with the wisdom compiled below.

5k Mile Intervals: the Happy Place

The original accepted OCI for a synthetic oil engine was 5k miles. This was a 66% increase in range for an oil that could easily perform twice as long, twice as well as 3k mile dinosaur oil. Totally reasonable outcome.

This is the interval I recommend to ALL of my customers, which I also practice on my own vehicles. It’s easy to calculate and remember if you do it on schedule, and it allows most folks to drive 5-8 months on a single oil change, performing just 2 oil changes per year instead of 1.

With premium fluids and filters, and a 5k mile OCI, most engines will run strong and live forever, like Duncan McLeod in Highlander…or Robin Williams in all of our hearts.

A 5k mile OCI leaves little to chance, and it keeps clean, stable oil moving through your motor’s veins at all times. If you forget and go over by 1000 miles, or even 1500, guess what? With the filters and fluids we use here in our shop, you’re still covered, so long as you don’t let the oil level run low. The motor will survive.

(more on this issue further down)

Real World Case Studies…

-My 1994 Toyota Camry turned 29 this year, with 265k miles, still sporting the original engine and transmission. Its oil looks clean and stable for up to a full year (driven ~5k spirited miles annually). Motor still has clean, consistent compression across all 6 cylinders. It’s not a 1-off case, either.

-My 2005 GTO that I personally built, tested and raced for 10 years had a hand-assembled 640hp race engine that lasted 11 years, 50k miles, and over 1000 passes. 5k mile OCIs, premium fluids and filters; 3k mile OCIs during a race season.

-My 2017 VW GTI has a 2.0L bottle of soda under its hood…makes an honest 350bhp from the stock IS20 snail…was purchased new…and has only ever known OE filters and fluids (at 5k mile LCIs).

That engine runs smoother now than it did off the lot, and the oil stays clean and level for all 5k miles. It’s one of the few Euro engines I’ve encountered that doesn’t require oil adjustments every ~1500 miles.

Let all of this sink in for a moment.

Additionally, every customer engine I’ve ever opened that’s been run on 5k mile LCIs has looked clean and healthy inside, well into its senior years beyond the 100k mile mark.

It really is that big of a deal, and the cost for this engine health is minimal.

10k mile OCIs, and beyond?

Now you’re all caught up. Let’s attack this long OCI deal head-on.

While plausible for folks who do mostly highway commuting at reduced engine speeds, 10k miles is also a LONG time for the drivers who are hard on their cars, or who use their vehicle for commercial purposes, such as delivery and mobile services.

Can the synthetic oil in your car handle this? Maybe. In a fully optimal, controlled scenario. But that’s not realistic. And this is why there is no uniform scenario in which a 10k mile OCI is safe and effective for ALL drivers.

Further, there are some very real shades of grey you need to be aware of.

Let’s consult the car-makers first. They’d know best, right? They built the motors! They’d never lie to us…

[insert catalog of automaker cover-ups and scandals from the last 100 years HERE]

https://www.carvertical.com/blog/top-10-worst-car-recalls-in-the-automotive-industry

Subaru North America has their vehicles on a 6k mile oil change interval, making them the most conservative in the game. Their engines are almost entirely horizontally opposed “boxers” famous for oil leaks, head gasket woes, and overheating in some instances, so this is a smart play. They also have a strong history of brand loyalty amidst their owners and followers. Let’s call them the outlier for this discussion.

A 6k mile OCI is totally reasonable if the owner is checking their oil level every couple of months to be smart and responsible. Tipping my hat to you, Subaru.

“非常によくやりました。” (Hijō ni yoku yarimashita. – “very well done!”)

But we’ve gone too far…

BMW, VW, Audi, Lexus, Toyota, and others have been putting their customers on a 10k mile OCI for many, many years. Some dealers even push for 15k intervals. It’s absurd, if we’re honest, and one of the biggest scams since the modern EV.

Some customers delight in the reduced service visits. Others voice concerns: is this really the smart play?

If you ask your local mechanic and engine builder [raises hand like Lisa Simpson], the true benefit of a prolonged OCI is 100% in the pockets of the dealers and OEs, and not in the consumer. Going this long is, for most drivers, a “fool’s errand.”

I have personally seen or touched hundreds of broken engines in which failure to check/adjust oil levels and change it on schedule was the cause of premature death. The simplest variable to manage is the one American motorists ignore the most…

Since Goat Automotive and its media author are data-driven, I’ll show you “the how and why” of the latest scam in the auto industry:

“Free is better! Right?”

Many car makers have been incentivizing buyers by offering a complimentary maintenance plan for the first 1-3 years of new car ownership: where oil changes, tire rotations, and in some instances…wiper blades and air filters, are all covered.

Volkswagen North America effectively HAD to do this in order to stay relevant in the US market after decades of unreliable powertrains, and a mixed bag of customer experiences in the service department.

This Oprah-esque business model for prepaid maintenance was game changing when it was first introduced to the American market, a market who had previously labeled dealerships as con artists and charlatans worth avoiding.

Check out the benefits of this new “free dealer services” business model:

1) It removes the chance of the consumer going to a sketchy, subpar “fast lube” joint and having a teenager cause costly engine damage, which happens REGULARLY to clueless consumers at “Spiffy Lube” and “HalMart”…that’s honestly a win for consumers. Well played, Patrick Mahomes.

2) It keeps the customers coming back to the dealer, which gives them time to walk around and inspect the newest models “just in case.” Because Americans never trade in perfectly functional products just to have a new model, right? [coughs in Apple]

3) It allows the dealer to continue building some type of trust and working relationship with their customers, which increases their likelihood of buying another car from that brand or dealer.

4) In this instance, with the dealer/OEM footing the service bills in the beginning, a 10k OCI cuts the number of free paid services IN HALF for the OEM, as compared to the previous 5k interval model. A 15k OCI cuts it in thirds. Imagine that boardroom presentation at BMW HQ to the top brass when the idea first debuted… How to fool customers while reducing internal maintenance expenses by 66%.

5) If the engine fails to reach 100k miles, who loses? The customer, or the dealer? Customer will need a new engine (parts and service center $$$ for the dealer and OE), or they will buy a whole new car.

While this reality is transpiring behind dealership doors, the customer thinks they’re getting a great deal, and they sleep warm and fuzzy that night.

I could probably stop here and have most readers convinced, but there’s one last chapter that highlights why Americans will likely never know a true, safe 10-15k mile OCI.

Let’s probe the very real issues and mistakes American motorists make that prevent 10k OCIs from being viable:

1) Americans don’t check their oil. Almost ever. Most people under 40 I’ve worked with have no clue how to even open their hoods, let alone the basics for properly reading and adjusting the oil level on a dipstick.

I’m not pooping on them as a group: they simply weren’t taught these basic skills and habits by their dads. And learning man-stuff from dad was the tradition for most families in the 20th century – the glory days of the gas-powered auto.

So we’re starting off with a tremendous handicap. Dads were also [traditionally] the member of the household who hounded other family members to stay on top of vehicle maintenance, thus preventing unplanned breakdowns.

2) Some car engineers are so satanic that they don’t even equip the car with a dipstick. I’m looking at you, Germany and Sweden. Their reinvented-wheel engine relies entirely on an oil level sensor. And electrical parts never fail or malfunction, so that’s good...

3) Modern engines have tighter tolerances internally, and they use oil that’s about as thin as water to accommodate this condition. First it was 5W-20. Now 0W-20 for the last 10-15 years.

That thin oil is easily burnt off during normal driving:

…as oil vapor through the engine’s PCV system

…or it makes its way slowly past the oil control rings of the piston over time, getting into the combustion chambers and burning up.

In either scenario, the motor slowly drinks its own blood, and if the driver isn’t on top of checking their oil levels: engine go boom. Long before that coveted 100k mile mark.

Our driver is now shelling out $10k for an engine replacement, or taking a total loss on the car and getting into a new car payment…for $400-700/month, or $5-8k a year…for many years.

Remember that a car suffering an engine failure may not even be worth $10k in good running condition, and worth nothing with a failed powerplant.

Please revisit my original lede at the beginning of this article: $160-250 a year for 2-3 oil changes, 5k miles apart, or a cycle of consumer debt that could have been avoided. It gets worse, though. See #4.

4) Car-makers in the early 2000s began experimenting with “oil life indicators”, where the car had a percentage indicator on the dash that would tell you how healthy the oil was, and when it was due for service.

The problem is these systems were often mileage/time-based; overly optimistic; and couldn’t account for things like oil level, oil condition, driving styles, etc. Honda and GM ran into issues with this, as it was causing unplanned engine failures for YEARS. And it took a long time for the American consumer to catch on: stick to a reasonable, mileage-based OCI and you’ll almost never lose.

5) People running their cars for 10k mile OCIs most often sell or trade their cars long before the 100k mile mark, which lends to a semi-planned obsolescence. Consequently, we often aren’t seeing what happens to the motors during that first life cycle.

They end up with their 2nd or 3rd owners, where anything can happen with a used car that has miles on it. If engines are failing at 90-110k miles as a result of extended LCIs, and low-oil conditions, no one is going to make racket over it. “My car was old, it’s bad luck and it happens.”

But that same engine might have gone 50% further without an issue if it had been better maintained.

6) The last one is the stake I drive into the conscious minds of all my customers: COST ANALYSIS

Oil and filters are CHEAP. Even if you factor spending the extra coin for a premium quality synthetic and an OE filter, it’s nothing compared to the cost of a $7-11k engine replacement.

Yes. A new motor in today’s economy will run you upwards of 5 figures after all the parts and labor are accounted for. It’s a 20-30hr job on most cars, and it’s entirely avoidable in most cases, just by keeping clean fluids and filters in the engine.

So to wrap us up, there is no safe, compelling reason for you, the consumer and driver, to push an engine out to 10k mile OCIs, even if it’s possible.

Even if people have gotten away with it.

You can rob someone in broad daylight in downtown San Francisco in today’s political climate and get away with it. It doesn’t make it smart or ethical.

Be smart with your money. Never cheap out on basic maintenance with your car or home. Ditto for towels, pillows, and toilet paper. Don’t cut corners there either.

Like or comment below if you learned something from this article, and thank you for lending your eyes and minds!

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