if its your second oil change there would be no need to flush it in fact i wouldnt even bother flushing any engine!!! aarghh.... NO don't use them, i did once.... and i blew my engine within 5 minutes the addatives thin the oil so it runs down through the drain channels easier. trouble, this happens pretty quickly and it you give the bike too much revs, you run the serious risk of engine seizure. i managed to blow a honda maggot (usually unburstable engines!). seized a piston, snapped a con rod and punctured the engine casing. the white oil smoke plume could be seen for miles just warm the engine and drain as normal. if you change the filter at the same time you'll of replaced ~98% of the oil anyway. when manufacturers recomend oil change intervals, this is taken into account so as long as you stick with regular oil changes and do it properly with a new filter each time, there is no need to do anything else. again these additives do more harm then good stay well away from them just do the oil and filter as mentioned above