Before fitting the oil seal, it is essential to check that the oil seal, shaft and bore are clean and undamaged. The surfaces the oil seal will come into contact with must be free of sharp points or burrs. The sealing lip is fragile, so even minimal damage can cause a leak. It is also important that the shaft and bore are correctly finished.


An oil seal serves three crucial purposes within any machinery. First, it prevents the leakage of lubricants or fluids outside the seal, even under high pressure. This function ensures the effective operation of equipment, as sufficient lubrication is a key requirement for the smooth functioning of machinery. Second, it retains the lubricating oil within the machinery. This retention function reduces the need for constant maintenance or re-lubrication, saving time and resources. Third, the oil seal acts as a barrier against contaminants. It prevents dirt, dust, and other potential contaminants from entering the machinery, protecting sensitive parts from damage or wear.
Table 8 shows the housing design checklist.
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.