② Spring code

The cost of new spark plugs can range from as low as $2 to as high as $20 per plug. Cheaper spark plugs are often made of basic materials and may not last as long as more expensive options. On the other hand, high-quality spark plugs are made of premium materials such as platinum or iridium, which can resist wear and corrosion better than cheaper materials.

PTFE oil seals

Because of the higher temperature resistance of FKM, this material is also chosen for applications where higher speeds play a role, which raise the temperature at the sealing lip considerably. Usually, using FKM will result in a longer life than using NBR. This compensates the higher price of FKM compared to NBR, as an FKM does not have to be replaced as frequently. The low temperature resistance of standard FKM is limited to -15 ˚C.

When they are subjected to hot & pressured oil, or hot & pressured gas, they will compress. These seals reduce in size and become more compact. Afterward, they store the mechanical energy generated by the heat and pressure, which is why they can maintain a leak-proof mating surface.

If the car has a manual gearbox , select first or reverse gear and put the handbrake full on. Otherwise, disconnect the battery and remove the starter motor .

Another important factor to consider when choosing spark plugs for your MK7 GTI is the electrode material. The electrode material can vary between spark plugs and can have an impact on the performance of your engine. Copper, platinum, and iridium are common electrode materials used in spark plugs. Iridium spark plugs are often preferred for performance cars like the MK7 GTI due to their durability and ability to maintain a stable spark.