The 15,000 Mile Oil Change Myth: The Real Damage Done To Your Engine

As someone who’s owned many, many 2002-and-older cars with over a decade of automotive experience, I’ve always known oil change intervals to be the old 3-months, 3,000 miles rule – I’m betting that you probably have heard the same. Most modern cars nowadays recommend a 7,500 mile oil change interval, and some, like BMW, go by a 15,000 mile interval. While a lot of research has been done and a lot of engineers have put a lot of time into extending the service life of our engines, it’s a concept I have incredibly hard time reconciling with the old “Change the oil every 3,000 miles or else” mindset, especially considering who is on the hook when the problems from a lifetime of 15,000 mile intervals manifest at 110 or 120,000 miles. Unfortunately this isn’t just a case of automotive hypochondria. Service shops are seeing engines that happily ran for 300,000 miles a few years ago on shorter intervals are now barely making it to 150k. What’s more, manufacturers are starting to admit they’re wrong about such prolonged oil change intervals as time has passed and cars running these lengthy intervals are having problems are breaking, meaning manufacturers are having to send out recall after recall to shorten the intervals after a huge increase in warranty claims.

What horror is lurking under your Valvecover? Photo DaneWilson77 via BimmerForums

Why do I have such a problem with this lengthy oil change recommendation?
For Manufacturers like BMW, Ford and Mercedes that offer pre-paid scheduled maintenance services, it makes financial sense for them to push out the intervals as long as possible so they have to pay for as few as possible. While today’s oils are dramatically improved over the oil products of just a decade ago – with some even guaranteed for 15,000 miles, there are so many variables to wear and the contaminants that can end up in your oil that such a recommendation could be causing a lot of premature wear and gunking up the inside of your motor. After the warranty period is up, the manufacturer is totally off the hook for your engine, but the thing is, the long term harm of these short intervals probably won’t rear its ugly head till after 100,000 miles – at which point you might need an engine or a very expensive repair service. It’s almost planned obsolescence in action through mechanical failure by deliberate design. 

The result of waiting 60k between oil changes. Photos DaneWilson77 via BimmerForums

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How the engine was still running is beyond us. Another shot of what 60k between oil changes will do to the inside of your engine, even with Synthetic Oil. Photo DaneWilson77 via BimmerForums

In July 2013, BMW (and Mini) sent out a letter notifying owners that their oil change intervals were being shortened from every 15,000 miles to every 10,000 miles, without really addressing why the interval was set too long in the first place – and neglecting to mention any damage/sludging incurred by engines that had been running the 15,000 mile intervals in the interim.
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And BMW‘s not the only one. In fact, General Motors recently had to issue a recall for 800,000 vehicles to shorten their oil change interval from what their oil change monitors had been indicating, due to a high failure rate of mechanical parts at low mileage. So while yes, today’s oils will happily go much longer than 3,000 miles, a 15,000 mile interval is really pushing the limits. Remember, the most Oil Life Monitors aren’t actually checking your oil and that many variables from outside air quality to how hard you’re working your engine contribute to the rate your oil gets “dirty” or contaminated with particulate matter.

So, the real question is how safe do you feel trusting the manufacturer? For me, knowing that any repairs to the motor after 60k are coming out of -my- pocket and not the manufacturer’s, it’s all about peace of mind. Personally, I don’t trust the manufacturer’s recommendations, especially for break-in oil changes, and changed my oil myself at 1,000 miles after completing break-in because the dealer refused to. I will still be taking the car to the dealer for the 7,500 mile interval, simply to have it on record with the manufacturer that the change has been done at the time the manufacturer specified and all related monitors are reset. A 7,500 mile interval is reasonable IF you’re running a quality, full synthetic motor oil like Motul with a high quality oil filter is certainly a safer bet than waiting til 10,000 miles to have the oil and filter changed.

A clean engine from an owner who changes his oil every 5,000 miles. Photo by Jackcat559 via Bimmerforums

A clean engine from an owner who changes his oil every 5,000 miles. Photo Jackcat559 via Bimmerforums

“But what if my car has a Computer Oil Life Monitor”. Here’s the trick to that. The reality is, most of these systems (in the case of GM and Ford, for example) simply use an algorithm to “calculate” the oil life based on engine data – there is no sensor actually in your oil pan. It is software only, with no actual readings being taken from the oil. (GM engineers tout this lack of a sensor in the oil pan as a “feature”) While some BMW and Mercedes Benz models do indeed have a sensor in the oil pan, the sensors themselves can become contaminated as well.

For peace of mind, if you really want to find out what your oil change intervals are doing to your engine there are a couple sure-fire scientific means to check. You can send a sample of your used motor oil to an outside company, such as Blackstone Labs, for an inexpensive and comprehensive analysis that will tell you, in scientific terms, exactly what’s in your used oil. For a more immediate result and a better idea of how sludgy things are, remove the valve cover and take a look at the motor. If you see sludgy gunk like in these photos, you’ve got yourself a real problem.

Depending on your driving conditions and your specific vehicle, a safe oil change interval for a modern car may range anywhere from 5,000 – 10,000 miles (after completing break-in). However, many factors influence this – particulate matter in the air varies widely from area to area, the effectiveness of YOUR air filter plays a role, and whether you use petroleum-based or synthetic motor oil has an impact on how quickly your oil becomes contaminated and no longer effective. Your oil may be good at 10,000 miles or it may be spent at just 5,000 – no laboratory can 100% replicate the diversity of real world driving conditions so there will always be some variance. Use a high quality synthetic oil such as Motul (which actually frees up horsepower normally lost using inferior lubricants) and pair it with a high quality oil filter for best results. For peace of mind, most enthusiasts choose to opt for a 5,000 mile oil change interval to err on the side of caution.

So the question is, do you trust your oil change interval and monitor to keep your motor running for 100k, or change it more frequently and keep the car running to 250k and beyond? Can you afford to trust the manufacturers?

Can you afford to let this build up in your oilpan? Photo DaveWilson77 via BimmerForums

Can you afford to let this build up in your oilpan? Photo DaveWilson77 via BimmerForums

Sure, you can trust the manufacturer, but after 100,000 miles, the car’s your problem, not the manufacturer’s. Data hasn’t yet shown that synthetic oils and engine design alone are enough for motor oil to actually last beyond 10,000 mile service intervals. The best insurance is physically checking your oil yourself every few weeks to ensure that the oil level is where it should be and to check that it’s free from visible dirt or particulate matter. Should it be a thick sludgy mess or are able to see particles in it, it’s probably time to change your motor oil. 

Regardless of who’s right, the cost of changing your oil too soon over the life of the car is STILL dramatically less expensive than fixing the problems caused by engine oil failure. As the old saying goes, “An ounce of prevention is worth a pound of cure.”

Story by Nicholas Gregson

Photo Sources: BimmerForums.com, BobIsTheOilGuy.com, E90post.com

Also Consider:

Aside from the harm of extended oil change intervals, oil changes done by personnel that don’t care about your car can be almost as detrimental – horror stories of quick-oil-change shops over torquing drain plugs, not reinstalling undertrays/splash guards/skidplates and worse are almost as common as tales of unnecessary upsells at shops not really trained to handle today’s sophisticated performance engines. Should you need a BMW Oil Change (or any other make or model, for that matter) done by a shop that will do it right the first time with the finest quality motor oil for your engine, trust the Modification Experts. Our Full-Service Install Shop in La Habra can change your oil with Motul or other synthetic motor oils and properly install high quality filters and treat your car with the care it deserves – and our highly experienced Installation Technicians can handle virtually any performance installation or aesthetic upgrade. Call 714-582-3330 to speak to a Modification Expert and make an appointment today.

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About Nick Gregson

Nick Gregson was born in Long Beach, CA and grew up exposed to the booming car-culture scene in Southern California at the dawn of organized Drifting in the United States. After learning to drive, he became personally acquainted with the best backroads of Southern California, including Mulholland Raceway, Glendora Mountain Road and Ortega Highway behind the wheel of a red 280ZX. Years after learning to go fast on the street, Nick went legit and began racing in sanctioned autocrosses in 2005 and raced in a 1987 BMW E30 328E at the 2010 24-Hours-Of-LeMons at Buttonwillow. Currently, Nick owns and modifies a 2014 Ford Fiesta ST and is an involved member of the FiestaSTForum.com

View all posts by Nick Gregson
1 comments
m3ustang
m3ustang

The problem is that the new BMWs don't even have a dipstick.  Couldn't believe it when I got my 2013.  Ridiculous. I forced the dealer to change my oil at 1250 miles and again at 6250, and they kept telling me "You don't need to do it until 15000 miles." What a bunch of morons.