Can you sleep babies in a cot which is over 10 years old?

Red Nose recommends you use a cot that meets Mandatory Australian Standards.(AS/NZS 2172)
https://rednose.org.au/article/what-is-a-safe-cot

It is generally accepted by Safety Organizations in Australia to only use a cot that is less than 10 years old.
Cots that are older than 10 years, may no longer be safe due to wear & tear from regular use or they may not meet the Mandatory Standards, as set out below.
These standards are developed & monitored by Product Safety Australia (ACCC) who state the following:
Second-hand and heirloom cots can be a hazard to children because: 

• the spacing between the bars may be too wide and trap a child’s head or may be too narrow and trap a child’s arms or legs

• the corner posts of the cot may be higher than the sides and ends creating a strangulation hazard if clothes get caught on it

• the catches on the side of the cot may be easy for a child to undo

• older cots may be painted with lead paint that children might chew on and swallow when they are teething.

https://www.productsafety.gov.au/system/files/Safety alert — Cots.pdf

General information about cot safety is here:
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/household-cots