Iridium Spark Plugs

As a rule, Bosch recommends that you follow the replacement interval listed in your vehicle owners manual, however we highly recommend that you inspect (read) your spark plugs annually and replace as required, to insure optimum engine performance.

Yes! Bosch Spark Plugs meet or exceed warranty requirements of all vehicle and engine manufacturers, and when properly installed in accordance with the recommended application, will not adversely affect the emission control system of any vehicle.

Consumers are sometimes told by an automobile dealer’s service writer or mechanic that a brand of replacement spark plug cannot be used in the consumer’s vehicle during the warranty period. The claim is made that use of the brand will “void the warranty”, with the statement or implication that only the original equipment brand of spark plugs may be used. This, of course, tends to cast doubt on the quality of the replacement spark plug. That claim is not true. Under the Magnuson-Moss Warranty Act and general principles of the Federal Trade Commission Act, a manufacturer may not require the use of any brand of spark plug (or any other article) unless the manufacturer provides the item free of charge under the terms of the warranty.

So, if the consumer is told that only the original equipment spark plug will not void the warranty, they should request that the OE spark plug be provided free of charge. If they are charged for the spark plug, the manufacturer or dealer is in violation of the Magnuson-Moss Warranty Act.

Yes! See the Technical Info tab for the list of designation codes.

Perhaps the greatest innovation in spark plug design over the years is “pure platinum” technology, combined with multiple electrodes. As early as the 1960’s engineers recognized the value that platinum added to automotive plugs: it provides improved corrosion and erosion resistance and imparts a longer performance life than the standard copper core center electrode plug design. The use of platinum not only broadens the heat range beyond that achieved with a copper core center electrode design, but also provides extremely consistent performance, a reliable spark and a longer performance life.

To validate the improved performance of surface air gap plugs with a pure platinum core and multiple ground electrodes, extensive testing was conducted in the laboratory and in the field:

• The first test measured the energy transfer efficiency of the four-electrode platinum plug compared to conventional and other premium plugs with a single ground electrode. This certified laboratory test measured the additional pressure generated by the spark discharge in a pressure chamber. Higher pressure equals a higher energy transfer by the spark. The test showed that the four-electrode platinum plugs transferred more energy to the air/fuel mixture resulting in improved driveablility and lower emissions.
• As a spark plug wears via erosion and corrosion, the gap between the center electrode and ground electrode gets larger. The larger the gap, the more voltage is required to produce a spark, until the capability of the ignition system is exceeded and the plug misfires. It was found that the multiple ground electrode, pure platinum center electrode plug reduces gap erosion and increasing voltage requirements over time.
• Roush Industries, an independent test lab, measured the fuel consumption for the four-electrode platinum plug, as well as, that for original equipment and other premium single ground electrode plugs. Fuel savings up to 4.8% were found in the four electrodes, platinum core plugs. Tests were conducted in accordance with Federal Test Procedure 75FTP and HFE.
• Tests for carbon fouling were simulated in a cold cell by repeatedly cooling, starting and operating the engine without letting the spark plugs reach their self-cleaning temperature. This cycle does not let the spark plug reach its self-cleaning temperature and allows the formation of carbon deposits. The tests found that the four ground electrode spark plugs had up to 33% better cold restart reliability than conventional plugs.

YES! Racing, as it has for 100 years, provides a great developmental impetus and test bed for spark plug durability and performance, and what is learned at Indy or Darlington, or Le Mans helps improve the spark plugs installed in today’s cars or trucks. From the first Indy 500 won by Ray Harroun’s Marmon Wasp to the last 17 Indy 500 winners, and many in between, each have used Bosch spark plugs. Many premium passenger car spark plugs use multiple ground electrodes and precious metals, such as platinum, which are a direct result of their development and testing in long distance racing.

See the Technical Info tab for more details on how racing improves the breed of passenger car spark plugs.

Bosch guarantees that you will feel improved performance in your vehicle when using a spark plug of the Bosch Platinum Series (Platinum+4, Platinum2, and Platinum). However, if you do not experience quicker starts, smoother acceleration, and improved fuel efficiency, you can return the plugs with a dated sales receipt and Bosch will refund the purchase price of the spark plugs.

Glossary:
Multi Ground- Plugs with multiple ground electrodes are called multi ground. These plugs also use surface gap spark patterns and the multiple ground electrodes increase service life.
Surface Gap- Surface gap technology is when the ground electrode is to the side of the center electrode. There can be no ground electrode (racing applications), multiple ground electrodes (PT+4 and PT2), or a single ground electrode. These spark plugs have improved efficiency and a higher probability of igniting a lean air/fuel mixture.
Resistor- Many spark plugs have a special conductive glass seal between the center electrode and the terminal stud. This seal acts as a resistor in the plug which reduces the transmission of pulses of energy to the ignition cables. These pulses can cause Radio Frequency Interference (RFI) with electrical components in the car. For some newer cars, resistor plugs are required for effective communication between the plugs and the electronic ignition.
Radio Frequency Interference (RFI)- When the spark plug creates a spark, a high frequency burst of energy is created. If this energy was to travel through the ignition wires, it could cause interference with other sensitive electronic devices, such as the radio or electronic control units. The resistor in the spark plug reduces this energy before it causes interference with other electrical components.
Fouling- Fouling occurs when a plug becomes contaminated with fuel, oil, or other contaminates that prevent the plug from generating a spark. Most plugs today are designed to reduce fouling and become self-cleaning when they reach 500 degrees Celsius. However, short trips, low speed driving, improper spark plug heat range (too cold), improper timing, or an oil leak in the combustion chamber can cause a spark plug to become fouled.
Bridging- Over time, contaminants can build on the surface of the spark plug if it does not reach self-cleaning temperature often. These buildups can grow between the electrodes until they are actually connected by a bridge of contaminants. This will often cause misfire.
Flashover- Occurs when the spark does not jump between the electrodes within the combustion chamber, but instead jumps between the metal shell and the terminal on top of the plug. This will always cause a misfire since the air/fuel mixture will not be ignited. Bosch spark plugs have a ribbed insulator to prevent flashover.
Quenching- The purpose of a spark plug is to introduce enough heat into the combustion chamber to initiate a smooth burn of the air/fuel mixture. Quenching occurs when that heat generated by the spark is reabsorbed back into the ground electrode, the center electrode, and the ceramic insulation. To reduce quenching and ensure an efficient transfer of heat, Bosch Platinum+4 and Platinum2 spark plugs use surface gap technologies.