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Myth-Busting: Should you change your oil every 5000km?

How many times have you been told, or read it on the internet that you should change your oil either every 5000km or after the first 5000km of travel.

SEARCH THE INTERNET for anything related to oil or oil change and you’ll come across many sites and articles telling you it’s vital that the oil in your car be changed every 5000km. If it’s a US site, it’ll suggest something like, every 3000 miles.

Well, it’s nonsense, at least it is for modern vehicles. Practical Motoring spoke with Subaru Australia which said there’s absolutely no need to change the oil in your vehicle at 5000km, and that owners should stick to the schedule in their service manual. Right from the horse’s mouth.

Subaru suggested that it’s vital car owners only use the oil recommended for their vehicle and not try and cut corners and fill it with cheaper stuff as this will do more harm than good. Ninety-five percent of all oil, regardless of the car maker, is the same, Practical Motoring was told, but it’s the additional five percent that makes the blend unique for that model and erring from that is bad, Subaru said.

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Diesel engines are a little different and there are those who swear the oil should be changed at 5000km, and while that might be the case for older diesel engines newer common rail diesels should be able to go anywhere between 10,000-15,000 before requiring an oil change.

Of course, if your vehicle (petrol or diesel) is being subjected to harder work (which means shorter, stop-start journeys), then you might need to change the oil sooner. And that’s because engine oil works best when it’s warmed up. If it’s cold then it’s not able to pick up and absorb contaminants or lubricate and cool the bits that need lubricating.

Oil technology, particularly synthetic oils, is improving all the time and some engineers argue that changing the oil early means motorists are missing out on the benefits of that improvement. Indeed, one US outlet looked at the quality of oil in a vehicle at 3000 miles and 7500 miles and found there was no change in the oil quality or performance and deduced that changing the oil early would simply be a waste of money.

Indeed, the myth about changing oil early, at 5000km, is one perpetuated by service centres and goes against what most car manuals will recommend. So, if in doubt check your owner handbook and don’t rely on a sticker placed on the windscreen by your mechanic.

That said, those in the know will admit that if your car just sits around driving nowhere, or only to the church on Sunday and the accumulated travel is less than 3000km each year, then you’ll likely need to change the oil sooner than the manual will recommend. But that’s more to do with age and settlement than anything else. Some will argue that when the car is brand new there’ll be filings and the like that might get picked up and so you’ll need to change the oil to remove the oil filled with filings. Nope. The oil filter is designed to catch all that rubbish.

More than that, until the oil has a bit of circulation under its belt, more than 5000km, for instance, it won’t be properly bonding to metals and glazing the bits and pieces it needs to glaze and lubricate. You can think about oil in the same way you’d think about a mop and bucket; when you start out cleaning your floor then the water is clean, but as you go it picks up grit and becomes dirty. There’s still cleaning agent in the water but it doesn’t look clean anymore… oil in your engine is the same. It starts out looking translucent and very quickly darkens in colour; it means its doing its job. If you’re within the owner’s recommendation, then there’s no need to change just because it’s gone black. But, it’s once you exceed the recommendation that a problem could occur as you’re exceeding the life expectancy of the oil in your car.

For instance, I recently tested a Toyota HiLux and looked at its manual which recommended changing the oil at 10,000km. Now, if you’re desperate then you could change the oil at 8000km. That’s still a long way after the myth of 5000km changes, and changing the oil in your car is a cheap insurance policy, so I get why some want to do it early. Just don’t forget to change the oil filter at the same time.

I was discussing this with a friend of mine the other day, who’d read an article by a once well-respected motoring club that recommended changing the oil in all vehicles at 5000km. There are some very clever people at this club but, unfortunately, they’re not always the ones writing or proofing the articles. Changing the oil so often is a waste of time and often against the manufacturer’s recommendation; most manufacturers recommend an oil change at more than 10,000km. Only in extreme situations would they suggest changing it sooner than that, and then it would likely be only around 7500km. These different driving situations are usually called Mild and Severe, and Mild covers those who do a lot highway driving and Severe is for those who spend a lot of time stuck in stop-start traffic.

The key, as with all things, is to check your owner’s manual and not the ‘wisdom’ of the internet, ahem, except for this article. There’s no need to change your oil early, but there’s nothing really to say you can’t either, sure, you’ll spend more money than necessary but if you’re doing the oil change yourself then it’s probably swings and roundabouts. If you do want to change the oil, or have your mechanic do it for you, then also make sure the oil filter is changed at the same time.

Question: So, it’s a myth to change early at 5000km, but people still do it. Do you? If so, let me know why. See you in the comments.


Isaac Bober

Isaac Bober

Isaac Bober was born in the shadow of Mount Panorama in Bathurst and, so, it was inevitable he’d fall into work as a motoring writer. He began his motoring career in 2000 reviewing commercial vehicles, before becoming editor of Caravan & Motorhome magazine. He then moved to MOTOR Magazine before going freelance and contributing to Overlander 4WD, 4×4 Australia, TopGear Australia, Men’s Health, Men’s Fitness, The Australian, CARSguide, and many more.