13.12.2025

19 FATAL MISTAKES when CHANGING the OIL in your car that DESTROY the ENGINE of your used SUV car

By Vitia

Changing the oil in an SUV or used car seems like a simple procedure. However, thousands of owners make mistakes that drastically shorten engine life, raise fuel consumption, and lead to costly failures.

If you drive a second-hand SUV or a pre-owned car, this information is even more important: these engines already have previous wear and tear, and improper maintenance can be fatal.

Below you will find the 19 most serious and common mistakes that destroy engines when changing the oil, and how to avoid them like a professional mechanic.

Also, you can see these fatal errors, in the following video from the GARAGE SUV channel:

1. Not respecting the recommended type of oil

Each motor needs a specific viscosity. Using the wrong oil reduces internal lubrication, accelerates wear, and increases engine temperature.

2. Choose extremely cheap brands

Low-quality oils lose properties within a few kilometers and generate internal carbon deposits.

3. Not changing the oil filter

The filter accumulates metal debris, sludge and sediment. If it is not replaced, the new oil is immediately contaminated.

4. Ignoring mileage limit

Driving thousands of kilometers with old oil increases friction, engine noise and irreversible damage to pistons and cylinders.

5. Not checking the condition before buying a used car

Many second-hand vehicles drove with inadequate oils. Catching it early can prevent you from further repair.

6. Using miracle additives without diagnosis

Some oil “improvers” clog ducts and alter internal pressure.

7. Mixing Different Oils

Combining synthetic, semi-synthetic and mineral reduces performance and generates internal foam.

8. Not warming up the engine before changing

Cold oil retains impurities. With the engine warm, it flows completely and drags sediment to the emptying.

9. Coming up short on quantity

Riding at a low level causes accelerated wear, extreme friction and risk of seizure.

10. Exceeding capacity

Overfilling creates high pressure, damages seals, and affects overall operation.

11. Not checking for leaks

A small leak can slowly empty the crankcase and leave the engine without lubrication.

12. Reuse the Drain Washer

That little ring loses seal with each disassembly, generating drip leaks.

13. Over-tightening the cap

Many cars are left with damaged threads. If it breaks, oil loss is uncontrollable.

14. Not cleaning the filter area

Accumulated dirt can enter the engine when the new filter is inserted.

15. Ignoring Oil Pressure

After the change, it is mandatory to start the engine, leave it idling and check that the pressure is stable.

16. Choosing oil by fashion and not by technical specification

Each SUV, whether compact, medium or large, uses different lubricants. General recommendations are useless.

17. Not properly draining old oil

Leave part of it inside the crankcase, mix impurities with the new oil.

18. Do not replace oil according to climate or use

Hot climates, short urban journeys and loaded driving require oils with greater protection.

19. Not checking the date of manufacture

An expired oil loses protective additives and oxidizes faster.

Why are these mistakes deadly for used engines or SUVs?

Second-hand vehicle engines usually have more miles, small modified internal tolerances, and natural wear and tear. Therefore:

  • Need more precise lubrication
  • They generate more waste
  • Require superior quality filters

A minor mistake can be the difference between an engine that lasts for years or one that is destroyed in months.

Recommendations

  • Always use the exact oil recommended by the manufacturer
  • Change filter on each substitution
  • Don’t improvise unknown brands
  • Requires maintenance history when buying a used SUV

Your engine is the most expensive part of the vehicle. Taking care of it with responsible maintenance is your best investment!



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