What parts to change after buying a used car

In Brazil it is difficult to find a second-hand car that is sold with everything in order, so it is safer to do a good first service

Not every salesperson is honest (Photo: Sony Pictures | Reproduction)
By Eduardo Rodrigues
Published on 2026-01-08 at 10:00 AM

As the sale of new cars has fallen in recent years and at the same time there has been an explosion in the number of vehicles running on transport or delivery apps, buying a used one is increasingly difficult. Except in the cases of certified used cars or cars that were carefully owned and deliver the maintenance record, it is necessary to carry out some maintenance soon after purchase.

Doing this service may seem overzealous, but the first review after purchase is for you to have greater control of the car’s condition. From then on you will have fewer unforeseen events and you will need to follow the manufacturer’s maintenance plan.

SEE ALSO:

It is also important to note that ill-intentioned shopkeepers “make up” the car for sale, making it look beautiful and hiding defects. Not to mention the odometers turned on, which are still common.

If you are about to buy a used car or have already purchased one, check out the 7 services to do for peace of mind.

1. Run a scanner

Using,A,Car,Scan,Code,Reader,For,Repair,Diagnostic,And
Changing the mileage on the dashboard is easy, but some modules save the correct value (Photo: Shutterstock)

The car records the mileage in several modules. The value may have changed on the dashboard, but the actual will be recorded elsewhere. The mechanic can check this with a scanner.

If there is any discrepancy, it is better to return the car and ask for a refund of the payment, in addition to being considered fraud. This can also be a problem for you in the future when you resell the vehicle.

With the scanner it is also possible to check if there are error codes and faults in the car that have not been resolved.

2. Change all fluids

Shutterstock Oil change of the lubricant engine coming out of the crankcase
Not only the engine oil, but also the box oil and the coolants, brake and steering (Photo: Shutterstock)

Engine oil, power steering fluid (if any), brake fluid, gearbox oil and gearbox fluid are the essential liquids for the operation of the car. Their replacement must follow the provisions of the manual, but many drivers do not do this.

In the first revision, change all within the original standards, respecting the specifications. Write down the mileage of the change and from there stipulate the deadlines based on the maintenance plan.

During the change, ask the mechanic to check some details:

  • If the oil that came is thicker than the original, a sign that there are internal gaps and the previous owner tried to mask it;
  • If there is rust in the coolant, it may indicate that tap water was used and not the correct fluid.

3. Filters

dirty engine air filter shutterstock
The car has a few filters, all of which are cheap and easy to change (Photo: Shutterstock)

The car has filters for the air admitted to the engine, for the fuel, for the oil and for the cabin air. There are exceptions, such as some cars without the cabin filter and others without the external one for fuel.

In the first revision, replace all of them with new and quality ones. They are cheap, running with them already saturated affects the performance of the engine and, in the case of the cabin filter, can put your health in danger.

4. Candles

spark plug shutterstock
A set of new spark plugs ensures that the fuel is burned correctly (Photo: Shutterstock)

Candles are often forgotten when it comes to making up the car for sale. The used one can have them already on time for replacement, with a simple inspection the mechanic can assess this.

With new spark plugs, fuel burning is more efficient, ensuring not only adequate performance but also more economy. And, as always, use models similar to the original or better.

5. Brake pads

shutterstock mechanic changing brake pad
Good pads reduce braking space and take longer to overheat (Photo: Shutterstock)

A car with worn brake pads may pass this to the pedal or produce squeaks during braking. That’s why it’s common to put new tablets of low quality or even the wrong size when selling.

When buying a used car, include new, quality pads in the list of what to trade-in. No savings on the brake system.

6. Tires

Chevrolet Equinox Turbo Activ 2025 Green Cacti wheel detail
Sellers put new tires cheaper, it’s better to change them soon for a quality one to be safe (Photo: Chevrolet | Disclosure)

A common argument in used car ads is to list that it has new tires. It is practically a tradition to change the tires at the time of sale and put the cheapest one you can find, when they don’t have the old one rerun.

If your newly purchased used car has new tires, but from unknown brands, change them immediately for a good one. These cheaper models often have low durability or poor performance.

For those who are still looking for a used car, here’s a tip: if it has half-life tires, but a good brand, this may be a sign that the owner is careful. It is more positive to find one like this than with new tires of suspicious brands.

7. Shock absorbers

Mechanic changing shock absorber in car suspension
It is common to recover old shock absorbers anyway when selling (Photo: Shutterstock)

It is possible to detect a car with bad shock absorbers when it is stationary. If you start to shake the body and it keeps moving after being released, it’s a sign that they’re blown.

That is why it is common for recovered shock absorbers to be placed in used cars. It’s not about the refurbished ones done right, which are practically new, they’re old filled with oil and painted.

Just in case, it is recommended to exchange the ones that came for a set of new and original parts.

0 Comments
Comments are the sole responsibility of their authors and do not represent the opinion of this site. Comments with profanity and insults will not be published. If you identify something that violates the terms of use, please report it.
Avatar
Leave one comment