Originally Posted by matt h
well Yamaha dont make oil, it would be re badged Shell or something,as long as the viscocity is the same then i wouldnt hesitate!!
It's not just the viscosity that's important - the other letters are the important bit.
"S" for spark ignition engines
f,g,h and j as the oil grade improves.
A 10W/40 oil could be mineral, semi-synthetic or full synthetic and could cost anything from £2/l to £10/l because of the different quality.
An Sj car oil of the correct viscosity should be just fine.
I reckon it might be a semi-synthetic.