They say, Fully Synthetic is better at heat protection and Extended Drain Intervals ..

The Heat Protection can benefit any type of driving conditions.
Extended Drain Intervals can only benefit those who are frequently out of the City or Fleets because they easily achieve the 5000kms/3months interval which is a hassle for some so they chose Fully Synthetic to change it every 10,000kms ...

But what about the ordinary office guy who can't get 10,000 kms in a year but still wanted to use synthetic for the heat protection reason .. Ofcourse I don't wanna wait 2 years to achieve 10,000 kms before changing oil ...

So what's the proper drain interval for Semi-Synthetics & Fully-Synthetics using months instead of kilometers ??

If:

Mineral Oil = every 3months/5,000kms

What months should Semi & Fully be drain & change ???

Semi-Synthetic = ????/7,000kms

Fully-Synthetic = ????/10,000kms