Car Advice

How to do an oil change and replace the oil filter

Just as humans can’t survive without water your car won’t survive without oil. Thankfully this important DIY is relatively straight forward.

CHOOSING FRESH OIL for your car and removing the old is one of the most rewarding DIY jobs. It’s important to get the right engine oil and, even if you’re selecting oil recommended by the owner’s manual or the in-store directory, a quick read of our guide will help you understand the life-cycle of oil and why it’s important to choose the correct type.

What will I need?

  • New oil*;
  • New oil filter;
  • New sump plug washer (if required);
  • Closed-ring spanner and/or socket to fit sump plug (usually 14-17mm);
  • Oil filter grip (if required);
  • Oil drain pan*;
  • Filter mesh funnel;
  • Rag(s);
  • Appropriate work clothes (they may get very dirty/covered in oil);
  • Safety goggles (important when working under the car);
  • Disposable gloves;
  • Jack and jack stands (if clearance is an issue); and
  • Container for old oil and a disposal centre**;

*Check the owner’s manual or in-store directory to find the capacity of oil required for the engine.

For engine oil, try to buy a little more than what’s required.

For the oil pan, buy one that holds a higher capacity than the oil coming out.

**Before changing your oil start collecting old milk and juice bottles or use an empty oil container.

Old oil is toxic to the environment and has to be disposed of appropriately which means don’t put it in the rubbish bin at home. Most rubbish centres will dispose of oil as long as it’s in a sealed container (you may have to empty it into a trough). To find the nearest centre contact your local council or check the local council’s website for information.

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How long will it take?

If this is your first time or the car needs to be jacked onto stands, allow more than one hour. If the car has acceptable clearance to access the oil pan comfortably and you’re familiar with the process it may take as little as 30mins.

What is oil?

When crude oil is refined it produces petrol, diesel and base mineral oil, and it’s the mineral oil that is used to produce engine oil.

Engine oil is a lubricant which is pressurised in the engine by a pump and flows around the engine to minimise friction and heat between moving components. Without oil, components inside the engine would create too much friction and overheat causing engine failure.

The longer oil is inside the engine the more it deteriorates and the less effective it is, thus old engine oil can also lead to engine failure and hence why it is important to change the oil at the recommended service interval. Oil should also be changed more regularly if operating the vehicle in high stress situations such as racing, towing, driving off-road or in extreme environments.

Is all oil the same?

Mineral vs synthetic

No. There are many different types of oil, such as mineral, synthetic and semi-synthetic. Some contain more additives than others and all oils have a specific rating for its viscosity (thickness) that will match your car’s requirements.

Mineral oil has been used in motors since the 1800s and because it’s unrefined in chemical structure it contains unwanted molecules which can be detrimental in modern, high tolerance engines.

Synthetic oil is superior to mineral because the bad molecules are removed and then beneficial additives that improve lubrication, working life and high temperature tolerance are added.

Semi-synthetic oil uses mineral oil as its base and has some synthetic oil added to it, providing an affordable alternative to 100 per cent synthetic oil, but it’s base mineral oil means it stills contains impurities.

What do all the numbers mean?

Nearly all oil available in Australia has a SAE (Society of Automotive Engineers) rating which refers to how thick the oil is. The higher the number the higher viscosity (thicker) the oil is at that temperature – a SAE 20 is thinner than a SAE 30 which is thinner than a SAE 40 and so on.

The problem with a single SAE grade oil is that it’s only effective at its optimal operating temperature – thicker oil will work well when it’s hot but not when it’s cold, and thinner oil when its cold but not when its hot, so most new oils are multigrade.

Multigrade oil

Multigrade oil combines the cold start benefits of thin oil, say SAE 5, with the high temperature benefits of a thicker oil, say SAE 30. Such an oil is rated as SAE 5W-30. It’s easy to remember as the cold temperature viscosity is rated ‘W’ for winter.

The owner’s manual will also specify any standards that must be met such as API or ACEA, this can be checked on the label of the oil.

 

Additives aren’t a silver bullet

There’s a no end of additives promising longer engine life, improved economy and even ‘fixing’ a worn engine, but in reality they deliver little to nothing. As we’ve discussed, mineral oil contains molecules that can be detrimental to its performance and the use of additives can be just as bad. Quite simply, if you want the best oil possible, then buy a fully synthetic motor oil from a reputable brand and don’t add any additives.

Should I choose synthetic or non-synthetic oil?

Generally speaking, synthetic oil is better than mineral as it has less impurities and offers better lubrication at higher temperatures, lasting more kilometres between servicing.

Some years ago synthetic oils were not recommended for older cars (pre-1990) as they were harsh on seals and could leak, however, new synthetic oils have improved and, in most instances, should be fine to use. If your car is a newer model and has always been run on synthetic, you should not go ‘back down’ to a mineral type oil.

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How do I choose the right oil for my car?

Refer to the owner’s manual or walk into a car store and lookup the correct oil from the catalogue. Most owner’s manuals and store catalogues will recommend an oil that works well all year round, however, understanding oil viscosity ratings will help you choose the right oil for the situation you’ll be in.

Aim to get a little more oil than required and use the rest to top up when required or until the next oil change.

Shelf life

All oil has a shelf life and lasts longer if it is in a stable environment that’s not prone to frequent temperature changes. Generally, oil will last on the shelf for 3-5 years before degrading. If you notice any clumps in the oil, or it doesn’t appear consistent in colour and viscosity, stop pouring into the engine and take it back to the store. And hopefully you’ve used a funnel with a filter mesh.

Should I just get the widest viscosity range possible?

In theory, such an oil (widest viscosity range) would provide the best protection across all temperatures, but in reality the further apart the ratings are the more synthetic additives that are required. Oil additives tend to break down quicker than the base oil and lead to shear down (thinning) in viscosity and potential oil sludge problems if the oil is not changed at or before the recommended interval. Generally speaking, oil between 5W-30 (5W-20, 10W-30 etc) requires less additives than larger viscosity gaps (10W-40, 20W-50 etc). That said, if you plan to change the oil religiously, then it might not be a problem, but, it wouldn’t be our recommendation.

How often do I need to change my oil?

Check the oil once a month

Cars require the oil be checked when either warm or cold, so have a read of the owner’s manual to check.

With the engine at the appropriate temperature (cold/warm), locate the oil dipstick and pull it out. The dipstick location will be in the owner’s manual and usually has the word ‘oil’ on it. Remove the dipstick and wipe it clean with a rag then reinsert and pull it out again. Check where the oil film comes up to on the dipstick indicator, it should sit near full, but if it consistently drops towards empty there might be a leak and it will need to be checked out – an engine without oil will die.

Some vehicles do not have a dipstick and instead will show the oil level on the dash (check the owner’s manual).

Check the colour of the oil

Fresh oil appears translucent and looks like thin treacle (in colour), if it is black it needs to be changed. If the engine has been kept in poor condition the oil should be changed immediately and then changed again after 1000km. This will allow for any old oil deposits and sludge to be removed and then normal maintenance intervals can commence.

When to change

All engines should have their oil changed according to the manufacturer’s recommended service interval, either kilometres or months, whichever comes first.

It’s always better to err on the side of caution and change the oil sooner rather than later. According to noted 4WD service centre, Berrima Diesel, manufacturer oil and filter change recommendations of more than 15,000km should be considered only as ‘acceptable’. It claims the best practice, for a diesel engine, is to change the oil every 5000km and the filter every 10,000km. However, it does concede that newer common rail diesel engines could manage both an oil and filter change at 10,000km.

Will changing my oil affect my warranty?

Self-servicing isn’t covered by warranty, so we don’t recommend DIY servicing new vehicles. Doing an oil change isn’t a complete service either as it covers many other checks and tasks on the car.

Why should I change the oil filter when I change my oil?

While some will suggest alternative oil and filter changes, it’s good practice to change both at the same time, because of the fact the oil filter retains impurities from the previous oil. Oil filters are cheap – don’t skimp on it.

oil-catalogue

What is an oil filter and how do I select the right one?

An oil filter is just a metal can with a ‘mating’ hole and sealing gasket at one end to connect the filter to the engine block. Just inside the gasket are perforated holes, and this is where the oil is passed (under pressure) into the filter and through the filter inside which is usually made of synthetic fibre. The filtered oil is then directed back through the central hole in the bottom of the oil filter and directed back into the engine. The oil filter picks up sludge and contaminants from the oil as it ages. When the oil is due for a change the oil filter will need replacing too. Most car parts stores will have a replacement item and it’s best to ask an assistant or find the correct model in the store’s parts catalogue. If you choose the wrong filter it won’t fit correctly and could cause engine oil to leak and lead to engine damage.

How do I know if the mechanic actually changed the oil?

Before going in check the condition of the oil on the dipstick (it will probably be black) and using a marker pen mark the oil filter. When you pick-up the car it should have fresh oil on the dipstick and the filter should be new.

WHAT TO DO:

1. GET THE CAR READY

The engine should be warm (you could drive the car around the block) – but not hot – so the oil flows freely. If the car does not have acceptable ground clearance to access the oil sump then jack it up onto axle stands and ensure the car will not roll away by putting the parkbrake on and chocking the wheels. Always do this on level ground. Remove any plastic guards or bash plates preventing access to the sump plug and oil filter.

2. DRAIN THE OIL

Tip:

Before removing the sump plug understand that warm oil is about to pour out as soon as the plug is loose enough. It’s a good idea to have your PPE (personal protective equipment) on such as overalls, gloves and goggles, and have somewhere such as a small screw pan to put your sump plug so that you can inspect it while the oil drains. You’ll also want the oil pan nearby and ready to put in place as soon as the oil begins to pour. A method to prevent the sump plug falling into the oil pan is to unscrew it until it is finger tight then undo it the rest of the way with your fingers. You’ve been warned, this can get messy!

 

Most of the oil will drain out of the sump plug hole and a small amount from the oil filter. Remove the oil filler cap first so that when you undo the sump plug the oil flows smoothly and freely, otherwise you may create a partial vacuum or have the oil spurt out which could make a mess.

The sump plug should be loosened using a closed-ring spanner however if it is too tight a ratchet socket will be required. Sump plugs have a specific torque setting to prevent over tightening but in practice this information is generally not available and a closed-ring spanner tightened by hand provides an acceptable amount of torque.

When the plug is loose position the oil drain pan underneath the sump and using a gloved hand undo the bolt.

Once the oil has drained from the sump position the pan under the oil filter and unscrew it. If it’s too tight to be undone by hand you will need to use the oil filter grip.

Remove the oil filter and place it into the oil pan and wait for the oil to drain.

Disposing of oil

As explained at the start, oil should not be thrown in with general rubbish and most rubbish disposal centres will recycle it, so put the used oil to the side and pour it into the new oil container once you’ve finished the oil change.

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3. REPLACE THE SUMP PLUG

Clean the plug and check that the thread is in good condition, if the thread is no good buy a replacement. A bad plug can cross-thread itself in the oil sump and be a headache to fix.

Some plugs have a permanent o-ring that is reusable while others will have a washer that needs replacing, again, check the owner’s manual or ask in-store.

Screw the plug back into the sump and tighten with a closed-ring spanner by hand until tight. If using a socket you’ll need to be extra careful not to over tighten and thread the bolt.

4. REPLACE THE OIL FILTER

Clean around the thread and seal where the oil filter fits. Make sure any left over seal is removed but don’t clean the surface with an abrasive pad.

Put a thin layer of fresh oil around the rubber seal before fitting and screw the filter into position. The filter can be screwed tight by hand or by using an oil filter grip, but make sure not to over tighten.

5. PUT IN THE NEW OIL

New oil is poured into the filler cap hole on top of the engine but it can be messy business. Oil is thick and heavy and a full bottle can be hard to manage while holding the funnel so ideally you’ll be able to get a helper to hold the funnel for you at this point.

If the funnel is too long and flimsy to be practical for this purpose cut it shorter with a sharp knife.

With the funnel in the filler hole, slowly pour the oil into the funnel making sure all the oil is going into the engine, it’s important not to try and rush at this point. If any oil spills on the engine simply wipe it off with a rag when you’re done.

It’s important not to overfill the engine with more oil than recommended – doing so can result in oil leaks and air being introduced into the oil, potentially causing serious damage. To prevent doing this, fill the engine to within 1 litre of its capacity, so if it has a capacity of 4 litres pour in around 3 litres. Oil bottles have an indicator level, usually on their side, that mark each litre. So if you’re pouring 3 litres in from a 5 litres bottle, pour until there’s two litres left.

Replace the oil filler cap, turn on the engine and allow to idle for several minutes while checking for leaks. If all is good then follow the oil level checking procedure as per the owner’s manual and fill until just on full.

 


Alex Rae

Alex Rae

Alex Rae grew up among some of the great stages of Targa Tasmania, an event that sparked his passion for all things mechanical. Currently living across Bass Strait in Melbourne, Alex has worked for the last decade in the automotive world as both a photographer and journalist, and is now a freelancer for various publications. When not driving for work Alex can be found tinkering in the shed on of one his project Zeds or planning his next gravel rally car.