I use 10/40w, have used various brands over the years as local stockists have discontinued with some brands. Only one to avoid was comma semi syn stuff in yellow can, cheap but caused cluch slip and poor gear changes in 2 engines of mine. I've switched to Morris brand as it's half the price of silkolene and I'd rather do changes often than buy very pricy stuff and dump it after a mere 1500 - 2000 miles. Several years commuting use, no problems, nothings needed any attention other than checking tappets so no wear going on.
