Hi Bjorn, I live in Australia and I use Genuine ´Honda´oil GN4, 10w-40 SJ. You may need a different viscosity where you live. My brother owns a 900 Bol-dor that has over 300,000 klms on it and still going strong. He adds ´Slick 50´ (about 450mls/oil change.) to his engine oil. I was getting around 280 klms to 17 ltrs of premium unleaded fuel and after I started adding ´Slick 50´ to my oil I am now getting 280klms to 14 ltrs of fuel. I haven´t done anything else but add the ´Slick 50´.