How often should you replace your spark plugs? 90% of car owners are doing it wrong!

In car maintenance, spark plugs are often overlooked, yet they directly affect engine ignition efficiency, power output, and fuel economy. Many car owners believe "as long as the car can still run, there's no need to replace them," resulting in increased fuel consumption, decreased power, and even engine vibration. In fact, spark plugs have a defined replacement cycle, and their lifespan varies greatly depending on the material and the usage environment.

This article will guide you through understanding how often to replace automotive spark plugs, what the criteria are, and what the consequences are of not replacing them.

1. What Is the Function of Automotive Spark Plugs?

The core function of automotive spark plugs is to ignite the air-fuel mixture. When the engine is running, the spark plug generates an electric spark under the action of high-voltage electricity, igniting the air-fuel mixture in the cylinder, thereby pushing the piston to do work.

If the spark plug's ignition efficiency decreases, the following will occur:

• Difficulty starting
• Unstable idling and vibration
• Weakened power
• Increased fuel consumption
• Deteriorated exhaust emissions

Therefore, although small, automotive spark plugs are a crucial component for the normal operation of the engine.

2. How Often Should Spark Plugs Be Replaced?

Many car owners mistakenly believe that spark plugs should be replaced every 20,000 kilometers, which is incorrect. Different materials used in car spark plugs have completely different lifespans.

(1) Ordinary Nickel Alloy Spark Plugs

Replacement cycle: 15,000–20,000 kilometers
Advantages: Inexpensive
Disadvantages: Electrode wears quickly, short lifespan

(2) Platinum Spark Plugs

Replacement cycle: 40,000–60,000 kilometers
Advantages: High temperature resistance, good stability
Disadvantages: Moderate price

(3) Double Platinum Spark Plugs

Replacement cycle: 60,000–80,000 kilometers
Suitable for vehicles requiring high ignition stability

(4) Iridium Spark Plugs

Replacement cycle: 80,000–100,000 kilometers
Advantages: High ignition efficiency, long lifespan
Disadvantages: Relatively high price

In short: There is no fixed replacement cycle for car spark plugs; it depends on the material and driving environment.

3. Why Do 90% of Car Owners Replace Spark Plugs at the Wrong Time?

(1) Focusing Only on Mileage, Ignoring Usage Environment

Urban congestion, frequent short-distance driving, and long idling times all accelerate the aging of car spark plugs. Even if the official mileage hasn't been reached, performance may already be declining.

(2) Ignoring Engine Performance

Many car owners don't check spark plugs as long as the car can still run. In reality, when power weakens and fuel consumption increases, it often indicates the car has entered a "performance degradation period."

(3) Using Inferior Fuel

Low-quality fuel easily produces carbon deposits, contaminating the spark plug electrodes and shortening their lifespan.

4. Five Obvious Signs of Aging Spark Plugs

If your car exhibits the following symptoms, it's likely time to check or replace the spark plugs:

• Slower starting or requiring multiple ignition attempts
• Weak acceleration and sluggish throttle response
• Engine idling vibration
• Significantly increased fuel consumption
• Pungent exhaust smell or black exhaust fumes

These are typical signs of decreased spark plug ignition efficiency.

5. What Are the Consequences of Not Replacing Spark Plugs in Time?

(1) Increased Fuel Consumption

Incomplete ignition leads to reduced combustion efficiency, requiring the engine to inject more fuel to maintain power output.

(2) Damage to Ignition Coils

Aging spark plugs cause the ignition coils to be under high load for extended periods, making them prone to burnout and increasing repair costs.

(3) Increased Engine Carbon Buildup

Incomplete combustion exacerbates carbon buildup, affecting the intake system and fuel injectors.

(4) Potential Problems With the Power System

Long-term unstable ignition can lead to increased engine vibration, affecting overall lifespan.

6. How to Choose the Right Spark Plugs for Your Car

(1) Choose According to Original Manufacturer Specifications

Including thread size, heat range, and electrode gap, all must meet the requirements of your car model.

(2) Upgrade Materials According to Driving Habits

Daily commuting: Platinum spark plugs are sufficient
High-speed driving and performance demand: Iridium spark plugs are more suitable

(3) Choose Reputable Brands

High-quality automotive spark plugs provide stable ignition, longer lifespan, and are more cost-effective in the long run.

7. How Often Should You Check Your Spark Plugs?

Even if it is not yet time for replacement, it is recommended to:

• Check the condition of car spark plugs every 20,000 kilometers
• Observe electrode wear and carbon buildup
• Clean or replace them early if necessary

Regular checks can prevent sudden malfunctions and improve driving safety.

Conclusion

Many car owners underestimate the importance of car spark plugs and wait until obvious engine problems occur before replacing them, often resulting in additional wear and tear. Regularly checking the condition of spark plugs can not only improve power performance but also reduce fuel consumption and extend engine life.