Mobil 1 is safe for any engine, and most tech writers for motorcycle magazines promote the use of synthetics. Mobil 1 redcap you are speaking of is a full synthetic. Blends are half synthetic and half conventional oil. I personally have been using Mobil 1 15w 50 in every vehicle I've owned since 1991, and wouln't use anyting else!!!! I used it in my '92 FZR600 after break in and every oil change after that until I traded it for my R6 this year. And as soon as my six is ready for next oil change it will get Mobil 1 in it....