What is the right engine oil for my car?
Tom Vondrasek | 30th May 2023 | 6 minutes to read
Engine oil is the lifeblood of your engine. Without it, your engine would stop very quickly. Much like if your heart stopped pumping blood. Both are catastrophic events. This is why it is important to select the correct engine oil for your vehicle, whether it is a daily driver, tow car, Sunday driver, 4-wheel driver or only used on special occasions.
Finding the right oil for your car might seem like a tricky prospect, with so many different brands, types, and viscosities out there, but it’s not as complex as you might think.
In this article we’ll go over some of the main things to look for in engine oil and answer some other burning questions you might have:
What Oil Does My Car Take?
There are various ways you can work this out. The owner’s manual will list it, Google it, ring a dealer that sells those vehicles or use our Rego Search function. You may even have a bottle for top ups from the last oil change so you can get the data from that. Our Rego Search works well, and it is not just oil you can find using it, you can find the oil filter as well.
When you search for motor oil the response is overwhelming as there are lots of different oil brands on the market and you are spoiled for choice, so make sure you’re thorough when choosing oil for your engine.
What Do the Numbers on Engine Oil Mean?
The large numbers on the engine oil bottle like 10W-40 or 20W-50 is the oil viscosity. Viscosity is how thick or thin an oil is and how easy is flows at a certain temperature. The only thing you need to find out is the viscosities that suit your vehicle’s engine. Engines are designed around the oil viscosities as this sets the tolerances of the moving parts. If you use the wrong viscosity, whether the oil is too thick or too thin, then it can cause the moving parts to wear out early as they are not being oiled correctly.
The first part of the number (20W) is viscosity when cold, the second part is viscosity when hot (50). The manufacturer may list a few different options though they should be similar or close to one another in viscosity. Always stick with manufacturer recommendations as they built the engine and understand it better than anyone. The danger with ignoring this is it could void factory warranty as well as damaging the engine.
If you would like a more detailed explanation of engine oil viscosities, check out our Know-How on ‘What Do the Numbers on Engine Oil Mean?’
What Type of Engine Oil Should I Use?
There are only 3 main types of engine oils:
- Mineral Oil – The earliest form of conventional oil made from refined crude oil that is pumped out of the ground. 20W-50 was the standard for engine oil for many years.
- Semi-Synthetic Oil – A synthetic blend oil that also has mineral oil in it. It gives some advantages of the full-synthetic oil like longer service intervals and reduced friction compared to a full mineral oil.
- Full-Synthetic Oil – Still made from crude oil though instead of refining it, they break it down to what is required and put it back together. That’s why it is man-made. Advantages are even longer service intervals and greatly reduced friction, giving greater fuel economy.
Ideally, the type of engine oil should be treated the same as viscosity, in that you should use what the manufacturer recommends. It is not as critical as viscosity as, if the viscosities match, then the type of oil is not as important.
However, it will likely be hard to find a mineral oil with the same viscosity as a full-synthetic. It will be easier to find a semi-synthetic oil that matches a mineral oil or full-synthetic oil viscosity.
There are a couple of other oils that we should mention.
Diesel Oils
Diesel oils are specially made for diesel engines. The oils specially made for diesels will have additives and properties designed to lubricate that type of engine, more so than a petrol engine. It will still be either a mineral, semi-synthetic, or full synthetic oil and both the viscosity numbers are just as important as a petrol engine, the oil itself is just designed to work better in a diesel engine.
High Mileage Oils
These are designed for older petrol engines that have done a lot of miles. This means their metal parts are worn and have a greater gap between them. These oils are normally a mineral oil, and the viscosity or thickness will have been slightly increased to compensate for the larger gaps. The additives and properties will be designed to help compensate for the engine wear. They are a good oil to use if your engine is using or burning a lot of oil in its day to day running.
How Often Should I Change the Oil?
How often you change your oil is based on the manufacturer’s recommendations. There are 2 things they look at: kilometres travelled and how long the oil has been in the engine. Both these things impact oil quality over time.
Kilometres travelled is easy as the engine is being used and at a certain point the oil and oil filter should be changed. If you have not done the required kilometres, then the second factor to consider is time.
Even though you haven’t run the engine the oil can still degrade from being used and just sitting in the engine and after a certain time it needs to be refreshed. Changing the oil filter as well is just good insurance for your engine.
If you are towing, in hilly country or on dirt roads, racing, or carrying heavy loads then it may need more frequent changes. Checking the oil regularly is good insurance. For one, it makes sure the oil levels have not dropped, requiring you to top it up. Even if you’re not doing any heavy work with your vehicle, it is still important to keep the correct amount of oil in your engine. As a matter of routine this should be checked every so often and it is always a good idea to keep a ‘top up’ bottle handy.
Monitoring your oil level on a daily basis will allow you to spot minor problems before they can become major, such as oil leaking or burning oil. The second part is to check the oil colour. If it has gotten dark before the required milage or time interval, simply change the oil and the filter.
You will find the more modern full synthetic oils have a longer service interval than the older mineral oils. Being custom made they are more durable than mineral oils. Their life cycle starts as a mineral oil’s finishes, and they can last twice as long or even longer. The flipside is that synthetic oil is more expensive than a conventional oil, so there are benefits and detriments to both.
Changing the Oil Filter
The other important and sometimes overlooked item is your oil filter. Golden rule, if changing your oil then please, please change your oil filter. Putting brand new clean oil through a dirty filter is never a good idea or clever cost saving. The dirty filter will contaminate the clean oil causing it to degrade quicker than putting it through a new filter. The old filter can also be restrictive, reducing oil flow to your engine — a bit like a clogged artery leading out of your heart.
If you’re in need of oil filters or engine oil from Castrol and Penrite to Valvoline, Repco has you covered, so head into your local store or shop online to top your engine up the right way.
