Can You (Truly) Go 20k Miles Without an Oil Change?

Can you go 20k miles without an oil change and still have your engine performing optimally in the short and long run?

Looked at from whatever angle, 20k miles is impressive – and isn’t something to take lightly, especially as regards engine oil.

So, the billion-dollar question is: can engine oil truly last 20k miles in an engine or is it mere marketing hype?

Let’s get into it from a car owner’s and a DIYer perspective.

No One Likes Wasting Money…

If you’re not a celebrity or were born into wealth, chances are that you don’t like spending money.

This is my reality and I can tell you for free that I don’t like opening my wallet all the time. This means, while the 6 months (or 5k) mile OCI that my manufacturer recommends appears great, why stop at that point if I can stretch things out comfortably without any adverse effect(s)?

This is exactly what I set out to do and for this, I bought the Mobil 1 Extended Performance for the weight recommended for my vehicle, 5W30.

And, this is what I have been using for the past 3-4 years until my supplier ran out of stock for the last change which forced me to switch over to Castrol Extended Performance, same weight.

So, is this something I’d recommend you undertake?

The answer is at the end of this piece; but first, a brief class on safety.

Are 20k Mile Oil Changes Safe?

Coming from a legal background, I look for, read and enjoy ‘fine prints’. When I decided to switch over to Mobil 1 Extended Performance, the first thing I did was look out for these prints.

Turns out there are some caveats:

1. The 20k mile or 1-year test (whichever is first) rule of Mobil is derived from the Sequence IIIH Engine Test (PDF). If your use case somehow puts more strain on your engine than this use case scenario this test is modeled after, running an oil change every 20k Miles or a year, whichever is first, won’t be the smartest thing to do with your vehicle’s engine.
2. The test fixture of the above is a 2014 Chrysler 3.6 L Pentastar port fuel-injected gasoline engine. If your vehicle is directly injected, it makes sense to conclude that you’re not covered, especially with the oil dilution challenges these engines are notorious for.
3. As per this source from Mobil, excluded services include commercial and racing applications; frequent towing or hauling; extremely dusty or dirty conditions; or excessive idling. If you live in a busy and congested place like New York or need to frequently cross the Sahara (for instance), running this OCI isn’t the best thing for you.
4. Use of the Extended Performance engine oil is predicated on also using a heavy-duty oil filter, capable of impressive oil filtration. Mobil 1 itself and Fram, to my knowledge, offer these filters.

As can be clearly seen, you can’t just slam Mobil 1 Extended Perfomance (or any Extended Performance engine oil for that matter) into your crankcase and expect results. There are strict rules to follow.

My Use Case Scenario

I thoroughly enjoy driving, but I also lead a very busy lifestyle, away from cars, the reality of driving, and vehicle repair.

This means I don’t drive much (generally). On some stretches (especially when the kids are on holidays), it’s perfectly normal for my daily driver to go up to a week without being driven.

As a result of the description I gave above, I hardly rack up miles on the vehicle.

For the past two years, for instance, the oil service reminder light only recently popped up, meaning it took two years for me to hit the 5k mile mark, which translates roughly to 2,500 miles, logged a year.

At this rate, were I to change engine oil at the recommended mark offered by Lexus (my vehicle manufacturer), this would amount to changing engine oil around the 1,250 mile mark for full synthetic good for at least, 5,000 miles.

It makes no economic or practical sense.

Extreme Precautions I Take…

Despite driving less than 5k miles a year, there are precautions I take to ensure that the Extended Performace engine oil I use actually gives me the best it can offer for the bucks:

1. I change oil filters at the 6 month mark, irrespective of mileage covered. The idea is not to overwhelm any one oil filter, despite using only oil filters rated for ‘extended drain’ or 20k miles (for the records, I use Fram Ultra Synthetic Oil filters).
2. I monitor my dipstick religiously, especially after the first six months. This is to make sure that the engine oil burned over time and the one lost during the oil filter change process do not negatively affect the quantity in the crankcase. For the past years, I’ve never had to actually top up.
3. I avoid excessive idling. I’d rather take a longer route than one laced with traffic. I also live in a city that is reasonable traffic-wise and I choose my hours carefully.
4. My PCV valve is properly taken care of and changed when clogged up. This helps minimize oil burn and overall, helps to keep things going nice and smooth.

How My Engine Looks at Almost 180k Miles

One of the biggest fears of keeping engine oil past its usefulness in an engine is that it begins to break down, failing to protect critical engine components as it should and while at this, forming sludge along the way.

With sludge, you know the game is closing in and you’ve been welcomed to trouble, officially.

Amazingly, all through the years, my engine has remained clean – devoid of any sludge build-up, proving that the one year OCI works for it, at least for my use case.

Here’s the engine as it is today:

20k Miles Without an Oil Change: Should You Do It?

Absolutely! Especially if you live in the developing world (as I do) where getting access to genuine engine oil can be a hassle. It makes no sense importing engine oil every six months and then, changing the same when it could still reasonably serve you for months/miles.

At nearly 180k miles too, my engine is still super clean, purrs like an adorable kitten and the engine performance is top-notch.

If your use case and caution level are similar to mine, then, you’ll thoroughly enjoy any good Extended Drain engine oil, irrespective of the brand you choose.

However, if you’re not sure or generally aren’t the most careful, the smartest thing to do is to follow your manufacturer, which in my case, would be six months or 5k miles – whichever is first.

That said, since the difference in price between regular synthetic engine oil and the Extended Drain equivalent isn’t much, it’s a smart move to invest the extra couple of dollars into something that you know can push past the OCI set by your manufacturer, even when you somehow forget to run your oil changes when they become due.

Will I press to 20k miles, if I need to? For highway miles, YES! For tortous city driving in stop and go traffic, NO!

Changing your oil every 5k miles could be a plain waste of money or it could be smart, common sense: only your use case and engine type will ultimately decide.

Good luck.

Want More DIY Content? Subscribe