Everyone has their own oil that is "the best". If all these manufacturers made crappy oil than they would be out of business. Seems like whenever there is an engine failure, people always blame the oil and not the particular parts or the engine tuner. In your book, they recomend a few brands of oil......but I'm sure that KTM has a deal with the oil companies to list them. Many people swear on castor, swear on semi synthetics, and swear on totally synthetic oils. They will tell you that synthetic for a 50cc engine is bad and that a castor oil will foul the plug. I have always found an oil that i could afford and that i like......and stayed with it. Once you choose your oil, stay with it and try not to listen to the guy next to you because every guy thinks HIS brand is the ONLY brand to go with. I say stick with the oil that you use on your bike to keep it simple.