IWC Schaffhausen Aquatimer Split Minute Chronograph Mode D'emploi page 28

Servicing your Aquatimer Split Minute Chronograph
Although the parts in this watch are all manufactured from top-quality
materials, a number of components are subject to natural wear and tear.
It is particularly important to ensure that the points at which wear occurs
are always well-lubricated and that oil contaminated by metal abrasion is
regularly removed. For this reason, we recommend that you have your
watch serviced approximately every five years. Please contact an autho-
rised IWC Official Agent or send your watch directly to the IWC Customer
Service Department in Schaffhausen.