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.

The depth of the bonded seal can be less and the space between the bore and the outside diameter can be changed for ease of fitting. The bonding of rubber to metal is an important factor to be considered in the manufacture of such seals and should be considered carefully, since failure of the bond will cause the seal to fail. The metal case of the oil seal is usually made from mild steel of deep drawing quality which enables blanking, punching, stamping of the steel to the required dimensions.

Modern engine oils, such as the current SG classification for gasoline engines, contain a large fraction of additives, many of which are detrimental to fluoroelastomers. The primary functions of oil-additive packages are to protect metal parts, avoid deposits in the engine, minimize oil degradation, and adjust fluid viscosity. Little attention has been paid to avoiding damage to rubber seals. Instead, elastomer producers have been expected to provide new, higher-performing products at no increased cost to auto manufacturers. Among the additives with moieties that may attack fluoroelastomers at high temperature are detergents (phenolates), dispersants (succinimides, alkylphenol amines), and antioxidants (amines, sulfides, hindered phenols).⁴ Many of these components are multifunctional, containing phenol or amine groups that can dehydrofluorinate and crosslink VDF-containing fluoroelastomers, leading to loss of elongation and eventual embrittlement. However, the rate and extent of reactions with seals are affected by many factors, including whether air is present in the system. When oil is exposed to air at high temperature, additives may undergo considerable changes. For example, a significant fraction of amines may be oxidized to amides, which have little effect on fluoroelastomers.⁵

Slide; don’t roll: While installing the o-ring, don’t roll it down, rather lubricate it so that it will easily slide down the shaft.