As per my understanding, it has done 150,000 on the odo; do the following:
1) Replace PCV valve.
2) Carry out engine flush with Liquimoly engine flush (you can find this on Pakwheels store) as per directions on the Liquimoly can.
3) Replace engine oil with 5W50 oil, yes 5W50 full synthetic with API SN certification. Any good brand is OK.
Note: Donot use 20W50, it’s too viscous for your car engine.