Raise the jack to take the weight of the engine off its mountings. Make sure you do not strain the radiator hoses or other connections. If in doubt, drain the radiator and disconnect the hoses (See How to remove a car radiator ).

In these instances, Viton can be the perfect sealing material for methanol/ethanol-blended gasoline. 

The oil seal gets its structural stability from an interior metal ring which serves as an inner skeleton. The outer skin is made of a more flexible material like nitrile rubber or other materials based on the physical environment of the seal. A spring on the lip of the seal supports the lip and keeps the lubricant from leaking. The lip construction is what blocks contaminants from outside.

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