What is the recommended engine oil grade for All New Honda CBR 150R released in 2016? Is it only 10w30 or 10w40 can also be used? The condition is pretty hot here, 30-40 degree Celsius here. 10w30 seems too thin.
What to do?
The bearing clearances were built to utilize 10W-30 motor oil. Using the thicker 10W-40 could cause engine damage over the long haul and will definitely hurt fuel consumption.
If the manufacturer has a warranty on the bike (which I bet Honda does), you'll be voiding the warranty.
If you are worried about the excess heat where you live, switch to a premium synthetic oil which will stand up to the heat better. Using a thicker grade oil than is recommended is not really a good choice.