lol just to give you a bit of reasoning behind what i said synthetic oil and im talking synthetic in the truest sense of the word, ie those oils which are completely man made (normally the very expensive ones ) can cause glazing of the bores on an RST i found this out the hard way as on my ol, old rst engine the bores were propely glazed... i did a bit of research and found out fully synthetic oil isnt good for an engine as old as an RST.