Hello all,
I have read on many different websites that for many companies, the serial number can show the date of manufacture of the bicycle.
Unfortunately, I haven't been able to find any websites for Apollo bicycles.
I Just got a vintage Apollo bike and the serial number on the bottom bracket is:

S4 5 106

Does this tell me anything about when the bike was made (or any other info at all)?

I read on this thread about a similar case, where the serial number was S0 8 XXX. In that case it was identified that it meant Aug 1980.
Following that logic, this would mean that my bike was manufactured in May 1984.
However, I'm don't understand how he came to the conclusion that it was an 80s bicycle. Was it based on other components?

Thank you very much in advance.

(Ps: this might be a silly question sorry I'm new to this.)