there is a difference... car oil just lubricates the motor, bike oil lubricates the motor, transmission, and clutch plates so it needs different additives, car oils also have different cleaners which are bad for clutch fiber plates... lots of people use car oil with no problem, but lots of people use it and get clutch slippage... theres no price advantage to using car oil so your right to stick with the bike stuff... a gallon of comp 4 is $24.99 so your looking like under 40$ for a semi-syn. oil change w/ filter

i used mobil one fully synthetic mx4t