In some cases, such as for enginr oils, additional functions are required such as cooling, corrosion protection, cleaning and suspension of pasty sludge formed during the use of the engine. These characteristics can be obtained only by modifying the basic oils (synthetic or mineral) through the use of special chemicals. In view of all the above, a first and simple assessment of the compatibility of the base oil with FKM rubber lead to exclude that the base oils may lead to important phenomena of chemical attacks. The work has involved six different oils that represent the generality of lubricants. The results of the aging test in engine oil show that changing the lubricant type it is possible to observe a not consistent behaviour in items made with different FKM rubber. As already mentioned, the swelling in oil always confirms that the base oil itself absolutely hasnt a solvent power with FKM. In performing the aging test in differential gear lubricant, the results obtained and the type of lubricant used for this second set of tests, show how important the selection and development of an FKM formulation is. The lubricants for automatic transmission do not seem to be an important limitation for seals or gaskets made of FKM peroxide type. The quick overview on the complex and wide world of oils is entirely the result of our direct experience. The aim and the purpose of this work is therefore to supply useful elements, dedicated to optimize the fluoropolymer compound choice destined to be contact with these lubricants.