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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.

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.


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Azmodan
Azmodan
2 years ago

Well what about a car making 430rwkw. Big boost turbo engines should be changing it more often, I only use fully synthetic ester based oils, and change it every 7500km (and filter). My wife’s bog stock Mazda 3 gets it changed every 15000km since it’s got no power.

If you use an oil by-pass filter you can greatly extend the life of oil. It’s the contaminants that shorten the life, and the by-pass filter will keep the oil viable easily 3-4x longer. Should be compulsory on diesel. All that black filth they belch out the back can be eliminated with a by-pass filter.

Ben Tate
Ben Tate
2 years ago

Isaac. Thanks for the story.

I change my oil every 10k kms. I use a FULL (GROUP 4) Synthetic oil. Not all oils labelled as synthetic are truly synthetic. Apparently, the Oil Co’s can label Mineral Oil as synthetic if they add an extra step in the refinement process. Some of the big names in Oil are selling oil that starts out as mineral oil and labelling it as synthetic. With the more expensive Group 4 synthetic I don’t mind running it out to 10k kms.

What about lawn mower oil? A mono grade is often recommended. Why? Let me flag this theory and see if it stands …

Additives are added to THIN monograde oil (SAE10) to make it a multigrade (SAE10W 30). But these additives wear out and the oil then reverts to its very thin SAE10 viscosity. Lawn mowers that rely on air cooling can run hottish and with very thin oil (because it hasn’t been changed since new) the engine is damaged. Using an SAE30 monograde oil (even though less than ideal for startup) reduces the risk of engine damage with hot thin oil. As stated, some of this paragraph is a guess on my part.

Next topic. Sunday’s Bathurst 11.5 Hour Race. Great to see real street cars at our iconic track. But just a tad that the Nissan GT-R was absent. Hope it comes back … with a 4L twin turbo V8. Congrats to Audi for equalling the Mazda RX7 record. Four wins each. There’s a MAJOR difference. I could afford an RX7. Maybe times have changed. We really need another race at Bathurst. An endurance tace for street cars UNDER $100k.

Ben Tate
Ben Tate
2 years ago

2. Group III – These synthetics are actually petroleum-based products that have gone through an extra refining process known as hydrocracking. This is a procedure where petroleum oil undergoes an additional process to eliminate more of the impurities found in crude oil.

3. Group IV – This type of synthetics are really thegenuine synthetics and 100% Synthetically Engineered PAO (Polyalphaolefins) oils. If you come across oil that recommends a drain interval of 25,000 miles, you can be sure this oil is made from a Group IV base stock.

Monty
Monty
2 years ago

I bought a 2003 Outback which my daughter drives. I did some research and all the Suby owner’s advice I found was to change the oil no later than the recommended distance. I was told that the Subaru engine has fine oil guides. If they clog up, goodbye engine. I’d be interested to know what other owner’s think.

Ben Tate
Ben Tate
2 years ago
Reply to  Monty

I heard a similar report about Commodores with the BOC 3.8L V6 engine. The claim was that fresh oil prevents a smallish oil galery (to the counter balance shaft or cam bearings?) blocking leading to engine damage.

2010krank
2010krank
2 years ago

I live in Canada. I had a VW Jetta diesel and would get the oil changed at Mr Lube. Every time I got the oil changed there they place on the inside of rhe windshield a sticker saying to change the oil in 5000km. I would point out that I am using synthetic and the change interval is greater but it made no difference. I think that the quick oil change locations are at fault for perpetuating this.

1250
1250
2 years ago

cock work ???? sorry not quite cock shore ?????? LOL !!

PracticalMotoring
2 years ago
Reply to  1250

Must be great to have never made a mistake. – Isaac

1250
1250
2 years ago

yep were all human , even you blokes !!!

Steve Bekkers
Steve Bekkers
2 years ago

a colleague didn’t service his camry for 2 1/2 years. then it started to blow lots of smoke a run like a sick puppy. anyhow my veedub schedules oil at 12k I do it at 10k, because I care..

Isaac Bober

Isaac Bober