A single page of lens care instructions.
It is important to keep in mind that with an older lens the oil released from the old aperture control grease is a source of internal fouling.
Internal lens mold cannot grow on a clean surface. The oil on the element surface, even a very thin film, serves as an abundant source of food for mold and bacteria.
The physics of lens design demands that all of the lens surfaces be perfectly clean for the lens to perform as it was designed to do. Even a very thin film of oil will drastically deteriorate the lens optical performance.
If oil is visible on the aperture blades this means that the oil has migrated throughout the entire lens and it is necessary to have the lens cleaned by a professional.