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Regular oil changes

Oil: vital lifeblood of your engine and the importance of regular changes

With the environment in the front of car makers’ minds due to stricter emission standards and regulations worldwide, it has never been more important to keep the oil fresh in your engine. Engine oil contributes heavily to the overall emissions of your car while playing a vital role ensuring happy motoring.

The modern motor car has many brilliant features. One part that can be often overlooked is the regular oil change.

Oil has a very important job to do in your engine. Not only does it lubricate all those moving metal components and stop them from welding and seizing to each other, it helps cool the engine from the heat of combustion, all those thousands of small internal explosions that occur every minute your engine is running. The oil helps dissipate that heat and at the same time absorbs minute particles of carbon, dust and varnish

(to name just a few of the nasties inside your engine). Over time the additives in the oil which do this will breakdown partly to the fact they can only handle so many heat cycles and stresses. They will also have captured as many of the carbon, varnish and dust particles as possible. The longer this process goes on, the more particles in the oil, eventually becoming sludge. The sludge is no longer viscous enough to be pumped through the engine’s internal passages causing irreversible damage due to metal on metal contact. It is always important to use a high quality oil when changing, however no oil will go forever - eventually they all breakdown.


Time and time again we regularly see infrequent and extended oil changes well above the minimum recommended by the manufacturer. An engine should stay internally clean if regular oil changes are carried out. Here are a few examples of engines with infrequent oil changes. The sludge is the black deposits on the metal components which should still be very silver.


Picture A is looking inside the top of a Toyota Kluger V6 petrol engine. This engine was replaced due to oil starvation from lack of changes. It had partially seized and was knocking internally due to excessively worn components. There was only 150,000 klms on the clock.

Picture A, Blockages from oil sludge

Picture B is the inside of the top of the secondhand replacement Kluger engine. This engine also had 150,000 klms on the clock. You can see there is a lot less black oil sludge accumulated in this engine and was quiet and smooth as it should be once installed.

Picture B, Clean inside fom regular oil changes

Picture C is the underside of a Toyota Yaris engine with the oil sump removed for inspection. There was 120,000 klm on the clock. The arrows indicate the accumulation of sludge on the sides of the engine.

Picture C, Oil sludge build up

Picture D again is the underside of the Yaris engine, this time a close up of the oil pickup which was blocked.

Picture D, Oil pick up blocked with oil sludge

On this occasion it was possible to clean the majority of this sludge out without needing to replace the engine. Only minor internal damage had occurred and no metal fragments were found in the sump once it was removed. 

These expensive repairs could’ve been avoided with more frequent oil changes. Oil is relatively cheap when compared to the cost of an engine replacement or a car. We always recommend frequent oil changes  between 5,000-10,000 klm depending on factors like age the of car, frequency and distance of trips and the types of driving you do, whether heavy towing, beach driving, track days.


Here at The Service Depot we only use quality Penrite lubricants and can tailor a maintenance plan to suit your driving needs.

Don’t let your car fall victim to damage. Call us today on (07) 3169 2333 to arrange your next oil change. The Service Depot Unit 15 Eureka Centre 29 Moreton Bay Road Capalaba 4157.

By Hayden Featherstonhaugh

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