After rigorous reconditioning by its owner, a used car may look almost new. Still, it's a good idea to have the car inspected by a trusted mechanic before you buy it. However, no matter how much pre-sale due diligence you conduct, there are certain things you need to do to ensure the vehicle's safety and drivability after you bring it home.
Step 1: Check the Oil
Using a dipstick can help you determine if there’s a need to change the motor oil in your new car. Look for these colors:
- Golden yellow color means the oil is new and still effective, and you don’t have to change it unless you want to switch to synthetic oil, which will provide improved wear protection.
- Dirty black coloration is a warning sign that the oil is mixed with excess sludge, grime and worn out engine components caused by friction. Replace it immediately.
- Milky brown oil is a serious warning sign that it is mixed with water, possibly because of an improperly fitted or a faulty oil filter. Change both the oil and oil filter to protect your engine from rust.
Step 2: Swap the Battery
Swapping is recommended because occasionally used cars are fitted with older or smaller batteries. To do this yourself:
- Put your vehicle in park, turn off the engine and set the emergency brake.
- Take care to avoid battery acid spilling on your clothes or car’s paint.
- Connect the red wire to the positive (+) terminal and the black one to the negative (-) terminal.
- The chemical reaction of the electrolyte in older batteries is less efficient compared to newer ones, and leads to a lower reserve capacity. This can make it more difficult to start your engine.
- Avoid using a small battery are if you live in cold weather. Its lower amperage output -- called cold cranking amps -- may not be able to start an engine in cold conditions.
Step 3: Flush and Bleed Brake Fluid
The owner's manual indicates when to change the brake fluid and should be your guide, but not many car owners follow the schedule. So don’t assume the previous owner replaced the brake fluid regularly -- or at all.
- Flushing is important because, as a car moves on the road, dust particles that flake off filtrate into the brake fluid.
- Water also finds its way into the braking system, as most brake fluids are too viscous and thick to withstand corrosion and heat in the wheel cylinders, rubber valves and calipers, which causes reduced stopping power. This compromises the effectiveness of the braking system -- and can lead to an accident.
Even if the previous owner has followed the brake fluid maintenance schedule, don’t assume the vehicle is safe to drive, because as air finds its way into the brake fluid, the brake system will come to feel spongy and its efficiency will be reduced. Have a mechanic bleed out the air to ensure your safety.
Step 4: Inspect the Tires
Even if the engine starts and the vehicle drives great, inspect the tires after taking ownership. A visual inspection of the tires can help you identify cracks and weak points. Wear protective gloves if you press the tires with your fingers, or press using blunt sticks that won't cause further damage.
Tires are made up of oils and chemical compounds (found in rubber) that break down or evaporate under prolonged exposure to UV rays. This causes sidewall cracking and tread separation as rubber becomes brittle and loses flexibility. While some of these cracks can swallow a coin, others are as thin as a hair and are not easy to detect due to dust particles, so you need to clean the tires first.
If you find major cracks, have a tire shop patch or replace the tires to avoid a blowout while driving. Even if your tires have sufficient thread, they could be mismatched. Check to see if they are all of the same brand or if there is a newer pair at the rear and an older pair on the front axle. While you may feel safe driving on mismatched tires, they could be uncomfortable even on a smooth-surface road; replace them as soon as you can.