I've just started learning about HP max oil changes and overhauls, best page explaining is "gt5 power variations explained" by MILOUSE, @
www.mygranturismo.net.. although it says max hp is at 187 mi. but i disagree, my gt academy gt-r climbed hp for quite a while, at 500 mi. i gave a oil change, didnt do much so at 1000 mi. i overhauled the engine and it did major help,, big difference, although ps3 glitches cuz at 1000mi. gt-r was at 868 hp so i went 2 the practice track to see if it would climb or decrease and instantly it showed that my hp was way down to 826hp def was late for overhaul..MILOUSE'S page is awesome cuz shows % of hp gained and/or lost. but what i dont get is he shows 3 stages of progression, from new 2 overhaul, mid-life to over haul, and high miles,, wonder if cars get even stronger, or if just takes longer to need services as time goes on,,?? hope this helps,, sure did me