@ZESTY, regarding the oil quantity, I have had the oil change of the GS150 and the mechanic always uses the 1 liter can; so I assume the quantity is 1 liter. As till now, I didn't had the oil filter changed.
@zaidi62, my GS150 just has 1200km mileage on it and during the initial running phase, the engine felt really hot, but this was back during the last summer's months and the bike was new. Now, at this stage, it doesn't heat as much as before and I hope the condition improves as the GS150 puts on more kms. I didn't lately check the fuel average and I hope it is around 40kms.