Spark plugs. Symptoms of wear and the best substitute.

Spark plugs are, contrary to appearances, a very important element of the engine. If they are damaged, it will not be possible to start the engine. Unfortunately, many drivers often forget about their regular review of spark plugs. Let’s check what symptoms most often accompany used spark plugs, and also whether it is worth trusting the cheapest as substitutes.

Spark plugs are the basic equipment for every gasoline engine. It is worth noting that they are not used in diesel engines, where we are dealing with self-ignition. Simply, spark plugs act as a lighter that ignites the compressed fuel and air mixture. They enable engine starting and also control fuel consumption. Their work takes place in extreme conditions when the temperature reaches even 1000 degrees Celsius. Like every vehicle component, the plug also has a life-span specified by the manufacturer, which is usually around 30,000. km.

The spark plugs are different

The mistakes often made by drivers and some mechanic is they believe in the purchase of universal spark plugs. Unfortunately, this type of decision does not just cost you money alone, but your time and also the risk of damaging your engine top cylinder.

A very important parameter when it comes to this part is its thermal value, i.e. the temperature at which the spark plug comes to work or ignites. As we can guess, it is set by the manufacturer and as in the case of the selection of engine oil, you should not change anything you fill is okay to use but to keep standards. Often there are cases when, after replacing spark plugs, the car starts to work incorrectly, and the fault lies precisely on the side of the incorrectly selected part. Inadequate spark plugs often overheat, causing the middle electrode to melt, and the exchange brings the opposite effect to the engine performance.

Symptoms of worn spark plugs

One of the most common symptoms of used spark plugs is an inferior performance, which however is not so easy to diagnose. Engine performance drop occurs slowly, which makes it difficult to make a diagnosis. However, if you feel the poor performance of the engine, it is worth starting the inspection (finding) just from spark plugs.

Failure is also often accompanied by an increase in combustion .

The easiest way to notice is the difficulty in starting the engine, most often on a cold engine state. Ignition problems are often caused by deposits that accumulate on the spark plugs, including refueling poor quality fuel, damaged gasket under the head or combustion of the engine with a large amount of oil. The problem can also appear if we often go on short distances. Then unheated spark plugs work below the temperature of self-cleaning, resulting in an excess of soot generated.

Worn out spark plugs very often also show undulating (having a smoothly rising and falling form or outline.) rotations of the engine, which is most easily seen if the car is running at idle.
The best way to check the condition of the spark plugs, however, will be to unscrew them. If you notice large black sediment on it, excess oil or molten electrodes, it’s a sign that it’s time to replace the spark plugs with new ones.

The best spark plug manufacturers


A leading manufacturer of spark plugs. Many brands use parts from this company when assembling brand new cars.

An interesting solution is the introduction of the LPG LaserLine series designed for use with gas-powered engines. The difference in the combustion of the gas and gas mixture is considerable and this is reflected in the state of spark plugs. In engines powered by LPG or CNG, it is often recommended to shorten the replacement of spark plugs by half as much as the manufacturer predicts. NGK solved the problem by developing spark plugs designed for gas-powered engines that are adapted to the combustion of this type of fuel mixture.

The other interesting model of this producer are candles made of iridium. They are very durable and have a high melting point.


One of the renowned spark plug manufacturers. This brand enjoys the considerable trust of customers. Bosch is a solid company when it comes to automotive parts that are also successfully installed in factory vehicles.

The Bosch offer includes spark plugs dedicated to gas-powered engines (Bosch Iridium). They are distinguished by a reduced thermal value due to the higher temperature at which the gas burns. This sparkplugs also have a smaller gap between the electrodes, which is related to the fact that the gas puts more electrical resistance.

For ordinary petrol cars without gas, I would recommend platinum spark plugs, which life reaches up to 100 thousand. km.

For people who are looking for savings, and they care about good quality equipment, I recommend nickel spark plugs also offered by Bosch.


Another leading manufacturer of spark plugs. Denso offers spark plug for many types of engines. It deserves praise among others TT line offering nickel and iridium spark plug.

Nickel plated electrodes are made of nickel alloy, which allows for a stronger spark and thus better ignition.

The Iridium TT line is one of the most durable constructions. The manufacturer specifies the lifetime of this type at 120,000. km. The electrodes are much thinner than in the case of the nickel spark plug, which significantly translates into their efficiency, lower combustion and more effective ignition of the mixture.

Spark plugs are a very important element of every vehicle. They must be operational so that the engine works properly and the combustion increases. When choosing a spark plug, I recommend that you follow the manufacturer’s instructions and choose them for the specific drive unit. In addition, the mileage at which the service was performed is worth saving, which will allow for the next exchange on time.

Please kindly stop adjusting the gaps with filler gauge I know that it solves a little of the problem to cover a distance but is still risky to your engine performance, If you are a mechanic please keep your standards at all times is better for the customer to go away with his car than for you to participate in bringing down your standards.

Please if you know other good spark plug manufacturer that you would like to draw our attention to please comments or write about it. Thanks for reading.


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