In fact, Australians have purchased a staggering 4.675 million new cars in the past 4 years, according to the Federal Chamber of Automotive Industries. That leaves a lot of vehicles that will soon be – or already have been – passed on to their second or even third owners.

In such a saturated market, it’s important to know what to look out for when buying a used car. Heed the advice of our 7 used car buying commandments to avoid being taken for a ride.

1. Pay attention to oil

Think of an oil check as an automotive blood test. A used car’s oil can tell you far more than any overeager salesperson or smooth-talking private owner. When performing your once-over, there are a few things to look out for. First, pull out the dipstick and check the oil level. It should read full, but not overfull. When you wipe the oil onto a cloth or tissue, it should be a light to medium shade of brown. Black oil shows signs of wear, and indicates that it hasn’t been changed for a considerable amount of time.

Next, unscrew the oil cap and take a look inside. Make sure there is no residue or build up around the cap or inside the engine block. Oil should be a light to medium shade of brown with no build up, discolouration or murkiness.

Use a torch to check the engine bay for signs of leaking oil, then thoroughly check underneath the car for seepage or leaks.

2. Check fluids

It’s not all about oil. While you’re under the bonnet, make sure you check the level and quality of the car’s power steering fluid, brake fluid, transmission fluid and washer fluid. Then check the car’s most important fluid – its coolant.

First, make sure that the coolant is full. Whether it’s blue, green or red, coolant should be clean and relatively clear. If it’s murky, brown or sludgy, step away from the vehicle with a swift “thanks, but no thanks.” Brown or sludgy coolant indicates oil contamination. If this is the case, your head gasket may need replacing, which can be an incredibly expensive procedure.

3. Suss the suspension

The state of a car’s suspension can tell you more than you might think. While you’re test-driving your prospective vehicle, don’t be afraid to introduce it to some tough terrain. Try to drive over a variety of road surfaces from smooth highway roads to potholed side streets. Notice how the car behaves on difference surfaces. Does it feel floaty and disconnected when going over bumps? How about harsh and rough? Both could be signs of worn suspension, along with squeaks, rattles, pops and groans.

4. Enforce a strict smoking ban

Blue smoke coming from the exhaust indicates a car is burning oil, black smoke – especially from diesel engines – indicates that a car is burning too much fuel and white smoke indicates it is burning coolant. Put simply, if it’s smoking, walk away.

5. Stop at nothing to avoid bad brakes

Brakes are a car’s most important safety feature, so it’s essential they’re in good working order. Squeaking or grinding is often a sign of bad brake pads. Wobbling in the steering wheel when you apply the brakes is a sign of an uneven or warped rotor, while a spongy or soft feeling when you brake could be signs of a failing master cylinder.

6. Say no to rust

Rust is a silent, sneaky killer. Start by examining external panels for tell-tale bubbling and discolouration, but don’t stop there. Other early signs of rust can be found at the bottom of each door (both externally and internally), in wheel arches and around the car’s windscreen, rear window, front and back bumpers. Check the engine bay and the underside of the car, especially exhaust and suspension components.

7. Check the paperwork

A lot can be hidden beneath the recently-polished surface of a used vehicle. To really know a car’s history, you’ll need to obtain its log books. A well-updated log book will tell you how often a vehicle has been serviced and what mechanical repairs have been carried out on it throughout its life – essential information for any new owner.

Make sure you check the Personal Property Securities Register before buying any second-hand vehicle. This will tell you if a vehicle has any money owing on it and may save you from buying a vehicle that could be repossessed.

Also take a look at the Register of Motor Vehicles when you check a vehicle’s registration expiry date online. This will tell you if the vehicle you’re looking at has been stolen, written-off or defected.

Finally, make sure you obtain the vehicle’s VIN number and engine number and make sure they match up with those on the registration papers. Any dealer or private seller should be happy for you to take the car to a mechanic for a check over pre-purchase.

When buying a used car, check out its Used Car Safety Rating online. There are lots of safe, less expensive cars to choose from. In fact, some of the most affordable used cars are among the safest.

With Takata’s recent airbag recall affecting millions of vehicles worldwide, it’s important you check ismyairbagsafe.com.au to make sure the vehicle you’re thinking of buying isn’t affected. All you’ll need is the car’s VIN or registration number.