Oil If you use a higher grade engine oil will it damage the engine of your motorbike?

Adding fuel to the fuel tank is absolutely unrelated to to any change in engine oil pressure.
The oil pressure will be higher when the engine oil is cooler and lower when the engine oil has warmed up.

If you are experiencing abnormally high oil pressure on start up I suspect you are running the incorrect type and grade of oil in the engine. Only use the oil specification(type and grade) listed by the manufacturer for your engine and nothing else.. If you are unsure what that is then it is specified in your owners manual for the vehicle.

High fuel consumption has also nothing to do with your engine oil pressure. If you are experiencing high fuel consumption then please read and examine these factors..........................
Finding and Fixing the Causes of Poor MPG

Noise could be lack of oil or wrong grade of gasoline.
Check your oil level.
If the noise is worse when the engine is working harder, like going up a hill, you should try higher grade of fuel, like premium.
Hope this helps.

Oil drain and refill with filter change 7.6 litres, Engine Oil Grade
API CF-4 (NEVER USE API CG-4)
ACEA B1, B3, B4, B5
5W30 is Good from colder than -30 to higher than +40 degree C
10W30 / 10W40 / 10W50 is good from -20 to higher than +40 degree C
15W40 / 15W50 is good from -15 to higher than +40 degree C
20W40 / 20W50 is good from -10 to higher than +40 degree C

SH/CD SAE 10W-30 grade or better engine oil.

Oil Capacity : 0.9 Liter (0.8 liters for routine change), oil filter change: 0.8 liters.

This is not uncommon with higher mileage engines. Use the AC Delco oil filter and a heavier grade oil to aid in compensating for wear. The heavier grade will stick around in the lifters longer. The right oil filter will aid in keeping line pressure too avoid start up knock.

The oil gets lighter as the engine heats up.
Was this problem there before you changed the oil? If no, thn the grade of the engine oil you have used (replace) could be of wrong specs., try using a higher grade.
Hope this helps!

SAE 10W30 SE motor oil for the crank case

No .. the SE and SF grades are obsolete .. The use of 5W verses 10W is that the 5W is lighter viscosity oil

sae 10w40, api classification sg, or higher.

do you mean higher grade as in better quality? If so No. If your talking about the rating numbers(example:10w30) you go by the lowest temp weather your riding will be in and highest temp weather. I don't know how that whole thing exactly works but the numbers deal with viscosity of the oil. Just use what the manufacturer of your bike tells you.