
oil tank gasket.


Figure 6: Oil seals for cars
(This prevents failure during mounting.)

Operating temperatures for engine oil seals (see Fig. 14.11 and cross-section of lip seal with garter spring in Fig. 14.22) vary widely, depending on engine design and location within the engine. Typically, the rear crankshaft seal is subjected to much higher temperatures than the front seal. Oil sump temperatures vary considerably, depending on provisions for oil cooling. This allows use of hydrogenated nitrile (HNBR), silicone, or acrylic elastomers for some seals in relatively low-temperature environments (120–140°C or 250–284°F). Standard fluoroelastomers (FKM), bisphenol-cured VDF/HFP/TFE terpolymers with 68–69% fluorine content, perform well in oil service up to about 160°C (320°F). More resistant fluoroelastomers are necessary for reliable long-term performance in more severe environments.
Oil seals increasingly had to meet higher requirements, which is why PTFE was developed in 1980. This variant can better withstand higher engine speeds, higher oil temperatures, longer oil intervals and modern lubricants. In addition, the oil seal contains a wider contact surface, which ensures less wear.


Both sealing types are popularly used in different mechanical engineering applications. How are they different? The article explains the fundamental working mechanism of both categories of seals.