I have a good condition Honda Pridor with 16500KM running. It's a great and economical bike. It gave me more than 50 km per liter on a 170+ kg payload. I have been using Honda Genuine 20W-40 Oil for the last 2 years. But as the summer approaches this year, it doesn't seem very convincing. My mileage also dropped to 42 km/hr. I am intended to continue 4 travels from Karachi to Hyderabad to Karachi.
I want oil suggestions, that I can buy for my bike (from a genuine agency ofc) that can maintain a healthy life for my bike even in harsh temperatures. I usually drive at 80 km/h+.
(Please give suggestions with genuine experience & logic 
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